mesa: Fix texture target validation for glFramebufferTexture()

Previously we were using the code path for validating
glFramebufferTextureLayer().  But glFramebufferTexture() allows
additional texture types.

Fixes piglit tests:
- spec/!OpenGL 3.2/layered-rendering/gl-layer-cube-map
- spec/!OpenGL 3.2/layered-rendering/framebuffertexture

Cc: "10.0" <mesa-stable@lists.freedesktop.org>
mesa: Implement GL_FRAMEBUFFER_ATTACHMENT_LAYERED query.

From section 6.1.18 (Renderbuffer Object Queries) of the GL 3.2 spec,
under the heading "If the value of FRAMEBUFFER_ATTACHMENT_OBJECT_TYPE
is TEXTURE, then":

    If pname is FRAMEBUFFER_ATTACHMENT_LAYERED, then params will
    contain TRUE if an entire level of a three-dimesional texture,
    cube map texture, or one-or two-dimensional array texture is
    attached. Otherwise, params will contain FALSE.

Fixes piglit tests:
- spec/!OpenGL 3.2/layered-rendering/framebuffer-layered-attachments
- spec/!OpenGL 3.2/layered-rendering/framebuffertexture-defaults

Cc: "10.0" <mesa-stable@lists.freedesktop.org>