SPV: Non-functional: Condense SPV-related versioning, and rationalize all uses.

Test/baseResults/spv.atomic.comp.out

@@ -2,7 +2,6 @@ spv.atomic.comp
 Warning, version 310 is not yet complete; most version-specific features are present, but some are missing.
 
 Shader version: 310
-Requested GL_ARB_gl_spirv
 local_size = (1, 1, 1)
 0:? Sequence
 0:14  Function Definition: func(au1; (global highp uint)
@@ -105,7 +104,6 @@ Linked compute stage:
 
 
 Shader version: 310
-Requested GL_ARB_gl_spirv
 local_size = (1, 1, 1)
 0:? Sequence
 0:14  Function Definition: func(au1; (global highp uint)

Test/baseResults/vulkan.vert.out

@@ -17,8 +17,8 @@ ERROR: 0:16: 'constant_id' : cannot declare a default, can only be used on a sca
 ERROR: 0:20: 'subpassLoad' : no matching overloaded function found 
 ERROR: 0:20: 'assign' :  cannot convert from 'const float' to 'smooth out 4-component vector of float'
 ERROR: 0:23: 'atomic counter types' : not allowed when using GLSL for Vulkan 
-ERROR: 0:24: 'shared' : not allowed when using GLSL for Vulkan 
-ERROR: 0:25: 'packed' : not allowed when using GLSL for Vulkan 
+ERROR: 0:24: 'shared' : not allowed when generating SPIR-V 
+ERROR: 0:25: 'packed' : not allowed when generating SPIR-V 
 ERROR: 0:32: 'initializer' : can't use with types containing arrays sized with a specialization constant 
 ERROR: 0:34: '=' : can't use with types containing arrays sized with a specialization constant 
 ERROR: 0:35: '==' : can't use with types containing arrays sized with a specialization constant 

Test/spv.atomic.comp

@@ -1,6 +1,6 @@
 #version 310 es
 
-#extension GL_ARB_gl_spirv : enable
+
 
 layout(binding = 0) uniform atomic_uint counter;