graphics/libplacebo: unbreak GLSLANG after r535260

src/meson.build:64:2: ERROR: C++ library 'glslang' not found

Running compile:
Working directory:  /wrkdirs/usr/ports/graphics/libplacebo/work/libplacebo-2.72.0/_build/meson-private/tmpnxxyvdwe
Command line:  c++ -L/usr/local/lib /wrkdirs/usr/ports/graphics/libplacebo/work/libplacebo-2.72.0/_build/meson-private/tmpnxxyvdwe/testfile.cpp -o /wrkdirs/usr/ports/graphics/libplacebo/work/libplacebo-2.72.0/_build/meson-private/tmpnxxyvdwe/output.exe -pipe -O2 -fstack-protector-strong -isystem /usr/local/include -fno-strict-aliasing -isystem /usr/local/include -isystem /usr/local/include -D_FILE_OFFSET_BITS=64 -O0 -fpermissive -Wl,--start-group -lglslang -Wl,--end-group -Wl,--allow-shlib-undefined

Code:
 int main(void) { return 0; }
Compiler stdout:

Compiler stderr:
 ld: error: undefined symbol: glslang::OS_GetTLSValue(void*)
>>> referenced by PoolAlloc.cpp
>>>               PoolAlloc.cpp.o:(glslang::GetThreadPoolAllocator()) in archive /usr/local/lib/libglslang.a

ld: error: undefined symbol: glslang::OS_SetTLSValue(void*, void*)
>>> referenced by PoolAlloc.cpp
>>>               PoolAlloc.cpp.o:(glslang::SetThreadPoolAllocator(glslang::TPoolAllocator*)) in archive /usr/local/lib/libglslang.a

ld: error: undefined symbol: glslang::OS_AllocTLSIndex()
>>> referenced by PoolAlloc.cpp
>>>               PoolAlloc.cpp.o:(glslang::InitializePoolIndex()) in archive /usr/local/lib/libglslang.a

ld: error: undefined symbol: glslang::GlslangToSpv(glslang::TIntermediate const&, std::__1::vector<unsigned int, std::__1::allocator<unsigned int> >&, spv::SpvBuildLogger*, glslang::SpvOptions*)
>>> referenced by glslang_c_interface.cpp
>>>               glslang_c_interface.cpp.o:(glslang_program_SPIRV_generate) in archive /usr/local/lib/libglslang.a

ld: error: undefined symbol: spv::SpvBuildLogger::getAllMessages() const
>>> referenced by glslang_c_interface.cpp
>>>               glslang_c_interface.cpp.o:(glslang_program_SPIRV_generate) in archive /usr/local/lib/libglslang.a

ld: error: undefined symbol: glslang::InitGlobalLock()
>>> referenced by ShaderLang.cpp
>>>               ShaderLang.cpp.o:(ShInitialize) in archive /usr/local/lib/libglslang.a

ld: error: undefined symbol: glslang::InitProcess()
>>> referenced by ShaderLang.cpp
>>>               ShaderLang.cpp.o:(ShInitialize) in archive /usr/local/lib/libglslang.a

ld: error: undefined symbol: glslang::GetGlobalLock()
>>> referenced by ShaderLang.cpp
>>>               ShaderLang.cpp.o:(ShInitialize) in archive /usr/local/lib/libglslang.a

ld: error: undefined symbol: glslang::ReleaseGlobalLock()
>>> referenced by ShaderLang.cpp
>>>               ShaderLang.cpp.o:(ShInitialize) in archive /usr/local/lib/libglslang.a

ld: error: undefined symbol: glslang::HlslScanContext::fillInKeywordMap()
>>> referenced by ShaderLang.cpp
>>>               ShaderLang.cpp.o:(ShInitialize) in archive /usr/local/lib/libglslang.a

ld: error: undefined symbol: glslang::InitThread()
>>> referenced by ShaderLang.cpp
>>>               ShaderLang.cpp.o:(ShConstructCompiler) in archive /usr/local/lib/libglslang.a

ld: error: undefined symbol: glslang::InitThread()
>>> referenced by ShaderLang.cpp
>>>               ShaderLang.cpp.o:(ShConstructLinker) in archive /usr/local/lib/libglslang.a

ld: error: undefined symbol: glslang::InitThread()
>>> referenced by ShaderLang.cpp
>>>               ShaderLang.cpp.o:(ShConstructUniformMap) in archive /usr/local/lib/libglslang.a

ld: error: undefined symbol: glslang::GetGlobalLock()
>>> referenced by ShaderLang.cpp
>>>               ShaderLang.cpp.o:(ShFinalize) in archive /usr/local/lib/libglslang.a

ld: error: undefined symbol: glslang::ReleaseGlobalLock()
>>> referenced by ShaderLang.cpp
>>>               ShaderLang.cpp.o:(ShFinalize) in archive /usr/local/lib/libglslang.a

ld: error: undefined symbol: glslang::HlslScanContext::deleteKeywordMap()
>>> referenced by ShaderLang.cpp
>>>               ShaderLang.cpp.o:(ShFinalize) in archive /usr/local/lib/libglslang.a

ld: error: undefined symbol: glslang::InitThread()
>>> referenced by ShaderLang.cpp
>>>               ShaderLang.cpp.o:(glslang::TShader::parse(TBuiltInResource const*, int, EProfile, bool, bool, EShMessages, glslang::TShader::Includer&)) in archive /usr/local/lib/libglslang.a

ld: error: undefined symbol: glslang::InitThread()
>>> referenced by ShaderLang.cpp
>>>               ShaderLang.cpp.o:(glslang::TShader::preprocess(TBuiltInResource const*, int, EProfile, bool, bool, EShMessages, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >*, glslang::TShader::Includer&)) in archive /usr/local/lib/libglslang.a

ld: error: undefined symbol: glslang::GetGlobalLock()
>>> referenced by ShaderLang.cpp
>>>               ShaderLang.cpp.o:((anonymous namespace)::SetupBuiltinSymbolTable(int, EProfile, glslang::SpvVersion const&, glslang::EShSource)) in archive /usr/local/lib/libglslang.a

ld: error: undefined symbol: glslang::ReleaseGlobalLock()
>>> referenced by ShaderLang.cpp
>>>               ShaderLang.cpp.o:((anonymous namespace)::SetupBuiltinSymbolTable(int, EProfile, glslang::SpvVersion const&, glslang::EShSource)) in archive /usr/local/lib/libglslang.a

ld: error: too many errors emitted, stopping now (use -error-limit=0 to see all errors)
c++: error: linker command failed with exit code 1 (use -v to see invocation)

Reported by:	VVD <vvd@unislabs.com>

graphics/libplacebo/Makefile

@@ -25,6 +25,7 @@ OPTIONS_SUB=	yes
 GLSLANG_DESC=		glslang SPIR-V compiler
 GLSLANG_BUILD_DEPENDS=	glslang>0:devel/glslang
 GLSLANG_MESON_ENABLED=	glslang
+GLSLANG_VARS=		LLD_UNSAFE=yes
 GLSLANG_IMPLIES=	VULKAN
 
 LCMS2_LIB_DEPENDS=	liblcms2.so:graphics/lcms2