mesa: add glsl version query (v4)

mesa: add glsl version query (v4)

Add support for GL_NUM_SHADING_LANGUAGE_VERSIONS
and glGetStringi for GL_SHADING_LANGUAGE_VERSION

v2:
  - Combine similar functionality into
    _mesa_get_shading_language_version() function.
  - Change GLSL version return mechanism.
v3:
  - Add return of empty string for GLSL ver 1.10.
  - Move _mesa_get_shading_language_version() function
    to src/mesa/main/version.c.
v4:
  - Add OpenGL version check.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=104915
Signed-off-by: Andriy Khulap <andriy.khulap@globallogic.com>
Signed-off-by: Vadym Shovkoplias <vadym.shovkoplias@globallogic.com>
Reviewed-by: Brian Paul <brianp@vmware.com>