[PATCH, libgo] Backport fix for compiler flags in mksysinfo.sh to gcc 4.9

[Lynn A. Boger]

Hi,

Please backport the change from 
https://gcc.gnu.org/ml/gcc-patches/2014-09/msg00713.html to gcc 4.9.

2014-12-30  Lynn Boger <labo...@linux.vnet.ibm.com>

    * libgo/mksysinfo.sh:  Add the same compiler flags used by 
configure to detect whether off64_t is present
       when generating the go structures for C types.  Otherwise the go 
type for off64_t might not be
       generated.


Index: libgo/mksysinfo.sh
===================================================================
--- libgo/mksysinfo.sh	(revision 218817)
+++ libgo/mksysinfo.sh	(working copy)
@@ -204,8 +204,10 @@ enum {
 };
 EOF
 
-${CC} -fdump-go-spec=gen-sysinfo.go -std=gnu99 -S -o sysinfo.s sysinfo.c
+${CC} -D_GNU_SOURCE -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE \
+  -fdump-go-spec=gen-sysinfo.go -std=gnu99 -S -o sysinfo.s sysinfo.c
 
+
 echo 'package syscall' > ${OUT}
 echo 'import "unsafe"' >> ${OUT}
 echo 'type _ unsafe.Pointer' >> ${OUT}