gi: fix unintended bool -> int cast and add glslang init assertion

src/gi/impl/GlslShaderCompiler.cpp

@@ -102,7 +102,8 @@ namespace gtl
   {
     // glslang requires this static initialization, however it internally
     // ref-counts and is thread-safe. The return value seems to be unused.
-    [[maybe_unused]] int r = glslang::InitializeProcess();
+    [[maybe_unused]] bool result = glslang::InitializeProcess();
+    assert(result);
   }
 
   GiGlslShaderCompiler::~GiGlslShaderCompiler()