Fix compiling error introduced by preprocessor

[Sway007]

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• Tests for the changes have been added (for bug fixes / features)
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What kind of change does this PR introduce? (Bug fix, feature, docs update, ...)

1. Fix compiling to GLSL error when exist global function contained in a macro and the function implementation include varying struct property access
2. Fix compiling to GLSL error when #define macro exist in #ifdef macro body, like the snippet below

   ......
   #ifdef xxx
     mediump sampler2DShadow scene_ShadowMap;
     #define SAMPLE_TEXTURE2D_SHADOW(textureName, coord3) textureLod(textureName, coord3 , 0.0)
     #define TEXTURE2D_SHADOW_PARAM(shadowMap) mediump sampler2DShadow shadowMap
   #endif
   
   float sampleShadowMapFiltered4(TEXTURE2D_SHADOW_PARAM(shadowMap), vec3 shadowCoord, vec4 shadowMapSize) {
   ......

3. Fix macro extend error due to preprocessor not ignoring comments