botan: Tell it that we use gcc explicitly.

It tries to deduce if the compiler is gcc or clang by looking for the
ending.

it searches for the -g++ ending but we pass -c++

srcpkgs/botan/template

@@ -31,6 +31,7 @@ do_configure() {
 	_args+=" --with-zlib"
 	_args+=" --with-sqlite3"
 	_args+=" --enable-shared"
+	_args+=" --cc=gcc"
 
 	case "$XBPS_TARGET_MACHINE" in
 	i686*)