A string literal immediately followed by an identifier (no whitespace) is
parsed as a user-defined-literal suffix since C++11. Modern clang has
turned the previously-permissive -Wreserved-user-defined-literal warning
into a hard error for this pattern:

  ap_UnixApp.cpp:868:29: error: invalid suffix on literal; C++11 requires
  a space between literal and identifier [-Wreserved-user-defined-literal]
          if(0 == strcmp (suffix, "."G_MODULE_SUFFIX))

Add the missing space so "." and G_MODULE_SUFFIX are two separate
preprocessing tokens (concatenated as adjacent string literals after
macro expansion, as originally intended) rather than one malformed
literal-with-suffix token.

--- a/src/wp/ap/gtk/ap_UnixApp.cpp
+++ b/src/wp/ap/gtk/ap_UnixApp.cpp
@@ -865,7 +865,7 @@
 		return false;
 	const char *suffix = file+(len-3);
-	if(0 == strcmp (suffix, "."G_MODULE_SUFFIX))
+	if(0 == strcmp (suffix, "." G_MODULE_SUFFIX))
 		return true;
 	return false;
 }