glsl: Link error if fs defines conflicting qualifiers for gl_FragCoord

GLSL 1.50 spec says:
   "If gl_FragCoord is redeclared in any fragment shader in a program,
    it must be redeclared in all the fragment shaders in that
    program that have a static use gl_FragCoord. All redeclarations of
    gl_FragCoord in all fragment shaders in a single program must
    have the same set of qualifiers."

This patch causes the shader link to fail if we have multiple fragment
shaders with conflicting layout qualifiers for gl_FragCoord.

V2: Restructure the code and add conditions to correctly handle the
    following case:

fragment shader 1:
layout(origin_upper_left) in vec4 gl_FragCoord;
void main()
{
    foo();
    gl_FragColor = gl_FragData;
}

fragment shader 2:
layout(pixel_center_integer) in vec4 gl_FragCoord;
void foo()
{
}

V3:
Allow linking in the following case:
fragment shader 1:
void main()
{
    foo();
    gl_FragColor = gl_FragCoord;
}

fragment shader 2:
in vec4 gl_FragCoord;
void foo()
{
   ...
}

Signed-off-by: Anuj Phogat <anuj.phogat@gmail.com>
Cc: <mesa-stable@lists.freedesktop.org>
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>

(cherry picked from commit 35f11e85cbe82b4bb77535e84e5515a5c49f67a6 with some
manual backporting)
glsl: Apply the link error conditions to GL_ARB_fragment_coord_conventions

Link error conditions added in previous patch are equally applicable
to GL_ARB_fragment_coord_conventions implementation. Extension's spec
says:
   "If gl_FragCoord is redeclared in any fragment shader in a program,
    it must be redeclared in all the fragment shaders in that program
    that have a static use of gl_FragCoord. All redeclarations of
    gl_FragCoord in all fragment shaders in a single program must have
    the same set of qualifiers."

Signed-off-by: Anuj Phogat <anuj.phogat@gmail.com>
Cc: <mesa-stable@lists.freedesktop.org>
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
(cherry picked from commit 9bcb0a85321c128b6e5ff8fc6694c2eff613e65a with some
manual backporting)
dri3: Enable GLX_MESA_query_renderer on DRI3 too

This should have happend around the time of commit 4680d23, but Keith's
DRI3 patches and my GLX_MESA_query_renderer patches crossed in the mail.

I don't have a working DRI3 setup, so I haven't been able to actually
verify this.  I'm hoping that someone can piglit this for me on DRI3...
It's also unfortunate the DRI2 and DRI3 can't share more code.

Signed-off-by: Ian Romanick <ian.d.romanick@intel.com>
Cc: Keith Packard <keithp@keithp.com>
Cc: "10.1" <mesa-stable@lists.freedesktop.org>
Reviewed-by: Emil Velikov <emil.l.velikov@gmail.com>
(cherry picked from commit 625bdd64e5ea3327d4459b1ccccff8dab89129d0)

Conflicts:
	src/glx/dri3_glx.c

During the cherry-pick, the following commit was squashed in as well:

glx: Conditionally compile GLX_MESA_query_renderer DRI3 support

Missed out with commit 625bdd64e5ea3327d4459b1ccccff8dab89129d0.

Cc: "10.1" <mesa-stable@lists.freedesktop.org>
Reviewed-by: Emil Velikov <emil.l.velikov@gmail.com>
(cherry picked from commit 0b307afd57082f0d4a0e8ba19093d313c9fb46ad)