Adding compile time check for subroutine functions with
the same names. Similar check for intrastage linking was already
landed in commit 5f0567a4f6.
From Section 6.1.2 (Subroutines) of the GLSL 4.00 specification
"A program will fail to compile or link if any shader
or stage contains two or more functions with the same
name if the name is associated with a subroutine type."
Fixes:
* no-overloads.vert
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=108109
Signed-off-by: Vadym Shovkoplias <vadym.shovkoplias@globallogic.com>
Reviewed-by: Tapani Pälli <tapani.palli@intel.com>
ad558408ff