glsl: fix compiler warnings in link_uniforms.cpp
glsl: fix compiler warnings in link_uniforms.cpp

With a non-debug build, gcc has two complaints:
1. 'found' var not used.  Silence with '(void) found;'
2. 'id' not initialized.  It's assigned by the UniformHash->get()
   call, actually.  But init it to zero to silence gcc.

Reviewed-by: Matt Turner <789b315743a28dd066a4ba1459c35951c291d8a6@gmail.com>

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