mesa: restrict formats being supported by target type for formatquery

The code just considered all formats as being supported if they were either
a valid fbo or texture format.
This was quite awkward since then the query would return "supported" for
e.g. GL_RGB9E5 or compressed formats and target RENDERBUFFER (albeit the driver
could still refuse it in theory). However, when then querying for instance the
internalformat sizes, it would just return 0 (due to the checks being more
strict there).
It was also a problem for texture buffer targets, which have a more restricted
list of formats which are allowed (and again, it would return supported but
then querying sizes would return 0).
So only take validation of formats into account which make sense for a given
target.
Can also toss out some special checks for rgb9e5 later, since we'd never get
there if it wasn't supported in the first place.

Reviewed-by: Alejandro Piñeiro <apinheiro@igalia.com>

src/mesa/main/formatquery.c

@@ -558,15 +558,29 @@ _is_internalformat_supported(struct gl_context *ctx, GLenum target,
     *         implementation accepts it for any texture specification commands, and
     *         - unsized or base internal format, if the implementation accepts
     *         it for texture or image specification.
+    *
+    * But also:
+    * "If the particualar <target> and <internalformat> combination do not make
+    * sense, or if a particular type of <target> is not supported by the
+    * implementation the "unsupported" answer should be given. This is not an
+    * error.
     */
    GLint buffer[1];
 
-   /* At this point an internalformat is valid if it is valid as a texture or
-    * as a renderbuffer format. The checks are different because those methods
-    * return different values when passing non supported internalformats */
-   if (_mesa_base_tex_format(ctx, internalformat) < 0 &&
-       _mesa_base_fbo_format(ctx, internalformat) == 0)
-      return false;
+   if (target == GL_RENDERBUFFER) {
+      if (_mesa_base_fbo_format(ctx, internalformat) == 0) {
+         return false;
+      }
+   } else if (target == GL_TEXTURE_BUFFER) {
+      if (_mesa_validate_texbuffer_format(ctx, internalformat) ==
+          MESA_FORMAT_NONE) {
+         return false;
+      }
+   } else {
+      if (_mesa_base_tex_format(ctx, internalformat) < 0) {
+         return false;
+      }
+   }
 
    /* Let the driver have the final word */
    ctx->Driver.QueryInternalFormat(ctx, target, internalformat,
@@ -969,10 +983,7 @@ _mesa_GetInternalformativ(GLenum target, GLenum internalformat, GLenum pname,
        * and glGetRenderbufferParameteriv functions.
        */
       if (pname == GL_INTERNALFORMAT_SHARED_SIZE) {
-         if (_mesa_has_EXT_texture_shared_exponent(ctx) &&
-             target != GL_TEXTURE_BUFFER &&
-             target != GL_RENDERBUFFER &&
-             texformat == MESA_FORMAT_R9G9B9E5_FLOAT) {
+         if (texformat == MESA_FORMAT_R9G9B9E5_FLOAT) {
             buffer[0] = 5;
          }
          goto end;