Apple's GCC block support was backported to FreeBSD's gcc-4.2.1 in base

(r260311).

With a small revision (r264121) which was MFCd to 10.0-STABLE as
r264214, our base GCC got the capacity to build more blocks application
cleanly.

This support is important for platforms lack support for clang like
ia64, powerpc and sparc64.

The attached patch:
- Overrides the clang port option in platforms that ship a valid
  block-enabled compiler in base.
- Let's platforms like powerpc and sparc use the base compiler.
- Adds license information for libdispatch (Apache License 2.0)

PR:		188332
Submitted by:	Pedro F. Giffuni <pfg@FreeBSD.org>

devel/libdispatch/Makefile

@@ -10,18 +10,16 @@ MASTER_SITES=	ftp://ftp.SpringDaemons.com/soft/
 MAINTAINER=	brooks@FreeBSD.org
 COMMENT=	Grand Central Dispatch API support library
 
+LICENSE=	APACHE20
+
+USES=		tar:bzip2
 USE_AUTOTOOLS=	aclocal autoconf
 ACLOCAL_ARGS=	-Im4
 GNU_CONFIGURE=	yes
-USE_BZIP2=	yes
 USE_LDCONFIG=	yes
 # This is needed because PIC support check in autoconf could fail for clang otherwise.
 CONFIGURE_ENV=	lt_cv_prog_compiler_pic_works=yes
 
-OPTIONS_DEFINE=	CLANG
-OPTIONS_DEFAULT=	CLANG
-CLANG_DESC=	Build with LLVM/Clang (required for blocks support)
-
 _MAN3=	dispatch.3 \
 	dispatch_after.3 \
 	dispatch_after_f.3 \
@@ -80,11 +78,17 @@ PLIST_FILES+=	${_MAN3:S|^|man/man3/|:S|$|.gz|}
 
 .include <bsd.port.pre.mk>
 
+.if (${OSVERSION} < 1000024)
+OPTIONS_DEFINE=	CLANG
+OPTIONS_DEFAULT=	CLANG
+CLANG_DESC=	Build with LLVM/Clang (required for blocks support)
+.endif
+
 .if ${OSVERSION} <= 800107 || (${OSVERSION} >= 900000 && ${OSVERSION} < 900002)
 IGNORE=	is not supported on this OS version
 .endif
 
-.if ${OSVERSION} > 900000
+.if ((${OSVERSION} > 900000) && (${OSVERSION} < 1000706))
 .if ${ARCH} == "powerpc
 BROKEN=		Does not configure on powerpc-9
 .elif ${ARCH} == "sparc64