Skinned shaders were exceeding maximum amount of vertex uniforms on amd hardware.

-Changed the transform matrix uniform to a 3x4 matrix and packed translation into it to free up uniforms. (3x3 is converted to 3x4 internally, so we were needlessly eating 3*52 extra uniform slots. translationPalette might also have been treated as a vec4 internally too, wasting 52 more slots.)
-matrix3x4 requires opengl2.1 and newer, so added a new featuretable mask.
-Also added a featuretable mask to disable hardware skinning and deferred shading on hardware with less than 1024 vertex uniforms.
NOTE: On old old old amd hardware, evidently a 3x4 matrix might be upgraded to 4x4. I'm unsure, but I doubt such hardware has 1024+ uniform components available to begin with. 4x3 supposedly doesn't do this, but opengl is column-major, so this makes little sense.

indra/llrender/llglslshader.h

@@ -100,6 +100,7 @@ public:
 	void uniform2i(const LLStaticHashedString& uniform, GLint i, GLint j);
 	void uniformMatrix2fv(U32 index, U32 count, GLboolean transpose, const GLfloat *v);
 	void uniformMatrix3fv(U32 index, U32 count, GLboolean transpose, const GLfloat *v);
+	void uniformMatrix3x4fv(U32 index, U32 count, GLboolean transpose, const GLfloat *v);
 	void uniformMatrix4fv(U32 index, U32 count, GLboolean transpose, const GLfloat *v);
 	void uniform1i(const LLStaticHashedString& uniform, GLint i);
 	void uniform1f(const LLStaticHashedString& uniform, GLfloat v);