Eliminate a reduce/reduce conflict in the function-like macro production.
Eliminate a reduce/reduce conflict in the function-like macro production.

Previously, an empty argument could be parsed as either an "argument_list"
directly or first as an "argument" and then an "argument_list".

We fix this by removing the possibility of an empty "argument_list"
directly.

metora/MesaGLSLCompiler,benaadams/glsl-optimizer,zeux/glsl-optimizer,KTXSoftware/glsl2agal,tokyovigilante/glsl-optimizer,adobe/glsl2agal,benaadams/glsl-optimizer,dellis1972/glsl-optimizer,zz85/glsl-optimizer,mcanthony/glsl-optimizer,bkaradzic/glsl-optimizer,benaadams/glsl-optimizer,KTXSoftware/glsl2agal,dellis1972/glsl-optimizer,jbarczak/glsl-optimizer,dellis1972/glsl-optimizer,jbarczak/glsl-optimizer,wolf96/glsl-optimizer,jbarczak/glsl-optimizer,KTXSoftware/glsl2agal,KTXSoftware/glsl2agal,metora/MesaGLSLCompiler,mcanthony/glsl-optimizer,tokyovigilante/glsl-optimizer,djreep81/glsl-optimizer,tokyovigilante/glsl-optimizer,bkaradzic/glsl-optimizer,wolf96/glsl-optimizer,bkaradzic/glsl-optimizer,adobe/glsl2agal,dellis1972/glsl-optimizer,zeux/glsl-optimizer,KTXSoftware/glsl2agal,jbarczak/glsl-optimizer,djreep81/glsl-optimizer,bkaradzic/glsl-optimizer,benaadams/glsl-optimizer,mcanthony/glsl-optimizer,wolf96/glsl-optimizer,mapbox/glsl-optimizer,jbarczak/glsl-optimizer,djreep81/glsl-optimizer,adobe/glsl2agal,zeux/glsl-optimizer,wolf96/glsl-optimizer,zz85/glsl-optimizer,wolf96/glsl-optimizer,djreep81/glsl-optimizer,adobe/glsl2agal,benaadams/glsl-optimizer,mcanthony/glsl-optimizer,mapbox/glsl-optimizer,benaadams/glsl-optimizer,zz85/glsl-optimizer,zz85/glsl-optimizer,dellis1972/glsl-optimizer,bkaradzic/glsl-optimizer,zeux/glsl-optimizer,mapbox/glsl-optimizer,mapbox/glsl-optimizer,metora/MesaGLSLCompiler,mapbox/glsl-optimizer,adobe/glsl2agal,djreep81/glsl-optimizer,tokyovigilante/glsl-optimizer,tokyovigilante/glsl-optimizer,zz85/glsl-optimizer,zz85/glsl-optimizer,mcanthony/glsl-optimizer,zeux/glsl-optimizer