Fix most clang warnings

- member initializing order in some constructors
- missing default branches in switch-case
- uninitialized variable if switch-case default (uncritical because
  program would exit)
- && and || brace warnings in if()

glslang/MachineIndependent/preprocessor/PpContext.h

@@ -86,7 +86,7 @@ namespace glslang {
 
 class TPpToken {
 public:
-    TPpToken() : token(0), ival(0), space(false), dval(0.0), atom(0)
+    TPpToken() : token(0), space(false), ival(0), dval(0.0), atom(0)
     {
         loc.init(); 
         name[0] = 0;