[Fix] (MG_State, MG_Backend): start TEXTURE_COMPARE_FUNC at LEQUAL

SamplerParameters defaulted compareFunc to ALWAYS, but GL 4.6 core table 23.18
and GLES 3.2 table 21.16 both say the initial value is LEQUAL - for sampler
objects and for the sampler state a texture object carries alike. Every freshly
created texture and sampler therefore answered GL_ALWAYS to
glGetTextureParameteriv(GL_TEXTURE_COMPARE_FUNC).

The Vulkan backend had been papering over it: ResolveCompareFunc substituted
LESS_EQUAL whenever a depth texture was sampled in compare mode and the func
still read ALWAYS, which fixed the rendering but also made an explicitly
requested GL_ALWAYS unreachable. With the default corrected that special case is
both unnecessary and wrong, so it is gone and the compare op is taken straight
from the sampler.

Takes direct_state_access.textures_defaults from failing to passing on both
backends.

MobileGL/MG_State/GLState/SamplerState/SamplerObject.h

@@ -66,7 +66,9 @@ namespace MobileGL {
         Float maxLod = 1000.0f;
         Float lodBias = 0.0f;
         Float maxAnisotropy = 1.0f;
-        SamplerCompareFunc compareFunc = SamplerCompareFunc::Always;
+        // GL 4.6 core table 23.18 / GLES 3.2 table 21.16: TEXTURE_COMPARE_FUNC starts at LEQUAL,
+        // for both sampler objects and the sampler state a texture object carries.
+        SamplerCompareFunc compareFunc = SamplerCompareFunc::LessEqual;
         SamplerCompareMode compareMode = SamplerCompareMode::None;
     };