glsl: add ARB_shading_language_include support to #line

glsl: add ARB_shading_language_include support to #line

From the ARB_shading_language_include spec:

   "#line must have, after macro substitution, one of the following
    forms:

       #line <line>
       #line <line> <source-string-number>
       #line <line> "<path>"

    where <line> and <source-string-number> are constant integer
    expressions and <path> is a valid string for a path supplied in the
    #include directive. After processing this directive (including its
    new-line), the implementation will behave as if it is compiling at
    line number <line> and source string number <source-string-number>
    or <path> path. Subsequent source strings will be numbered
    sequentially, until another #line directive overrides that
    numbering."

Reviewed-by: Witold Baryluk <witold.baryluk@gmail.com>