configure: Isolate UTF-8 env in a subshell

Do not leak LD_LIBRARY_PATH changes to rest of script.  They
break fakeroot and prevent subsequent commands like "chmod"
from working during debian package genaration.

sr_unix/configure.gtc

@@ -673,6 +673,7 @@ export gtm_chset
 
 # Now work on UTF-8 mode
 if [ "$doutf8" -ne 0 ]; then
+	(
 	# Ensure we ARE in UTF-8 mode
 	utflocale=`locale -a | grep -i en_us | grep -i utf | grep '8$'`
 	if [ $arch = "zos" ]; then
@@ -704,8 +705,7 @@ if [ "$doutf8" -ne 0 ]; then
 	fi
 	(gtm_dist=$gtmdist/utf8; export gtm_dist; cd $gtm_dist; ./mumps -noignore *.m; $echo $?>>$gtmdist/compstat; \
 	if [ $is64bit_gtm -eq 1 -o "linux" != $arch ] ; then $ldcmd $ldflags -o libgtmutil$ext *.o ; fi )
-	gtm_chset="M"
-	export gtm_chset
+	)
 fi
 
 # Change mode to executable for the normal binaries