autoconf: Remind developers to bump version numbers in configure.ac
autoconf: Remind developers to bump version numbers in configure.ac

Just like configs/default, the version number in configure.ac needs to
be bumped for releases. Maybe later we can figure out how to scrape the
version from configs/default into configure.ac.

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