Commit 68e04cc6

 was tested using automake-1.11.  Unfortunately, automake-1.12
made a "slightly backward-incompatible change" in the use of yacc with C++, and
for a .yy file, the generated header file is now named .hh, not .h

To work with both, write our own rule for running yacc, which generates a
header file named .h, rather than using automake's rule.

Also, remove things from BUILD_SOURCES which don't need to be there

Also, update EXCLUDE rules in doxygen/glsl.doxy, for change of generated files
from .cpp -> .cc, and glsl_lexer.h has never existed.

Signed-off-by: Jon TURNEY <jon.turney@dronecode.org.uk>