libgo: fix quoting in mksigtab.sh

    
    The quoting was causing us to never add the system-specific signals.
    
    The test for this is misc/cgo/testcarchive in the master repo, which
    we don't yet run for gccgo.
    
    Reviewed-on: https://go-review.googlesource.com/37453

From-SVN: r245776

gcc/go/gofrontend/MERGE

-893f0e4a707c6f10eb14842b18954486042f0fb3
+0bcc1bc98dca48af40d9f54f4eacbbafaa30beb1
 
 The first line of this file holds the git revision number of the last
 merge done from the gofrontend repository.

libgo/mksigtab.sh

@@ -56,7 +56,7 @@ echo '	_SIGSYS:    {_SigThrow, "SIGSYS: bad system call"},'
 # Handle signals that are not supported on all systems.
 
 checksig() {
-    if grep 'const $1 = ' gen-sysinfo.go >/dev/null 2>&1; then
+    if grep "const $1 = " gen-sysinfo.go >/dev/null 2>&1; then
 	echo "	$1: $2,"
     fi
 }