gl: Consider also ARB_shader_bit_encoding to enable bit conversion

On drivers only supportinmg OpenGL 3.3, like llvmpipe, ARB_gpu_shader5 may
not be available, but (u)intBitsToFloat and floatBitsTo* are part of GLSL 330,
and are also availabe by enabling the extension ARB_shader_bit_encoding.

Consequently, check for this extension when ARB_gpu_shader5 is not available,
require it when available, and enable the bit code path using these bit cast
functions accordingly.

Signed-off-by: Gert Wollny <gert.wollny@collabora.com>

renderdoc/driver/gl/gl_common.h

@@ -684,6 +684,7 @@ extern bool IsGLES;
   EXT_TO_CHECK(33, 30, ARB_texture_swizzle)                      \
   EXT_TO_CHECK(33, 99, ARB_occlusion_query2)                     \
   EXT_TO_CHECK(33, 99, ARB_timer_query)                          \
+  EXT_TO_CHECK(33, 30, ARB_shader_bit_encoding)                  \
   EXT_TO_CHECK(40, 32, ARB_draw_buffers_blend)                   \
   EXT_TO_CHECK(40, 31, ARB_draw_indirect)                        \
   EXT_TO_CHECK(40, 32, ARB_gpu_shader5)                          \

renderdoc/driver/gl/gl_debug.cpp

@@ -417,6 +417,10 @@ void GLReplay::InitDebugData()
       texSampleDefines +=
           "#define HAS_BIT_CONVERSION 1\n"
           "#extension GL_ARB_gpu_shader5 : require\n";
+    else if(HasExt[ARB_shader_bit_encoding])
+      texSampleDefines +=
+          "#define HAS_BIT_CONVERSION 1\n"
+          "#extension GL_ARB_shader_bit_encoding : require\n";
   }
 
   vs = GenerateGLSLShader(GetEmbeddedResource(glsl_blit_vert), shaderType, glslBaseVer);