glsl/preprocessor: Extract version directive processing into a function.

glsl/preprocessor: Extract version directive processing into a function.

Version directive handling is going to have to be used within two
parser rules, one for desktop-style version directives (e.g. "#version
130") and one for the new ES-style version directive (e.g. "#version
300 es"), so this patch moves it to a function that can be called from
both rules.

No functional change.

[mattst88] v2: Use intmax_t instead of int for version argument. Would
otherwise write garbage after #version since PRIiMAX was reading 64-bits
instead of 32.

[idr] v3: A later commit fixes the caller of
_glcpp_parser_handle_version_declaration to pass the correct number of
parameters.  Fix it in the patch that changes the interface instead.

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Acked-by: Carl Worth <cworth@cworth.org>