configure: Add -m32 flag for C++ compiler too.

configure

@@ -1967,6 +1967,7 @@ case $host in
     if test "x$enable_win64" != "xyes"
     then
       test -n "$CC" || CC="gcc -m32"
+      test -n "$CXX"|| CXX="g++ -m32"
       test -n "$LD" || LD="ld -m elf_i386"
       test -n "$AS" || AS="as --32"
       host_cpu="i386"

configure.ac

@@ -24,6 +24,7 @@ case $host in
     if test "x$enable_win64" != "xyes"
     then
       test -n "$CC" || CC="gcc -m32"
+      test -n "$CXX"|| CXX="g++ -m32"
       test -n "$LD" || LD="ld -m elf_i386"
       test -n "$AS" || AS="as --32"
       host_cpu="i386"

tools/winegcc/Makefile.in

@@ -7,7 +7,7 @@ DEFS = \
 	-DAS="\"$(AS)\"" \
 	-DCC="\"$(CC)\"" \
 	-DCPP="\"@CPPBIN@\"" \
-	-DCXX="\"$(CXX)\"" \
+	-DCXX="\"@CXX@\"" \
 	-DLD="\"$(LD)\"" \
 	-DPRELINK="\"$(PRELINK)\""