Fix SF # 614587, configure.in patch from Tim Rice

Need to quote $GCC in case it isn't set.
diff --git a/configure b/configure
index 8c7bf9b..6f338bc 100755
--- a/configure
+++ b/configure
@@ -1,5 +1,5 @@
 #! /bin/sh
-# From configure.in Revision: 1.344 .
+# From configure.in Revision: 1.345 .
 # Guess values for system-dependent variables and create Makefiles.
 # Generated by GNU Autoconf 2.53.
 #
@@ -3445,7 +3445,7 @@
 
 if test -z "$OPT"
 then
-	case $GCC in
+	case "$GCC" in
 	yes)
 		case $ac_cv_prog_cc_g in
 	yes)
diff --git a/configure.in b/configure.in
index e97e32e..fb49e1f 100644
--- a/configure.in
+++ b/configure.in
@@ -459,7 +459,7 @@
 AC_SUBST(OPT)
 if test -z "$OPT"
 then
-	case $GCC in
+	case "$GCC" in
 	yes)
 		case $ac_cv_prog_cc_g in
 	yes)