autoconf: Optional debug build with --enable-debug
autoconf: Optional debug build with --enable-debug

Allow the user to set the compiler debug flags and macros through the
option --enable-debug. This addes -DDEBUG to the macros and -g to the
CFLAGS and CXXFLAGS if gcc and g++ are in use.

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