The getsecs() function is implemented in platform- and bootfw-specific

files and, in a number of these places, there were problems with how they
were declared.

Some used int return instead of time_t. On some architectures the bit
width of time_t did not naturally fit into an integer and could lead to
some unexpected behavior. (For example, 32-bit ARM builds uses a 64-bit
time_t.)

Make sure the function prototypes always specify void for the argument
list when they do not have any arguemnts, otherwise some compilers can
complain about the prototype.

Reported by:	Kevin Zheng
Reviewed by:	sjg
Approved by:	sjg (mentor)
Obtained from:	Juniper Networks, Inc.
MFC after:	1 month
Differential Revision:	https://reviews.freebsd.org/D7463

sys/boot/efi/libefi/time.c

@@ -228,7 +228,7 @@ time(time_t *tloc)
 }
 
 time_t
-getsecs()
+getsecs(void)
 {
     return time(0);
 }

sys/boot/efi/libefi/time_event.c

@@ -76,7 +76,7 @@ time(time_t *tloc)
 }
 
 time_t
-getsecs()
+getsecs(void)
 {
     return time(0);
 }

sys/boot/i386/libi386/pxe.c

@@ -586,7 +586,7 @@ bangpxe_call(int func)
 
 
 time_t
-getsecs()
+getsecs(void)
 {
 	time_t n = 0;
 	time(&n);

sys/boot/ofw/libofw/ofw_time.c

@@ -41,8 +41,8 @@ time(time_t *tloc)
 	return secs;
 }
 
-int
-getsecs()
+time_t
+getsecs(void)
 {
 	time_t	n = 0;
 	time(&n);

sys/boot/powerpc/kboot/main.c

@@ -151,8 +151,8 @@ delay(int usecs)
 	} while (t < ti + usecs);
 }
 
-int
-getsecs()
+time_t
+getsecs(void)
 {
 	struct host_timeval tv;
 	host_gettimeofday(&tv, NULL);

sys/boot/powerpc/ps3/main.c

@@ -179,10 +179,10 @@ delay(int usecs)
 		tb = mftb();
 }
 
-int
-getsecs()
+time_t
+getsecs(void)
 {
-	return ((mftb() - basetb)*ns_per_tick/1000000000);
+	return ((time_t)((mftb() - basetb)*ns_per_tick/1000000000));
 }
 
 time_t

sys/boot/uboot/lib/time.c

@@ -47,7 +47,7 @@ time(time_t *tloc)
 	return (secs);
 }
 
-int
+time_t
 getsecs(void)
 {