mesa: Fix glCompressedTexSubImage (and non-Sub) for height == 2 or 1.

Generally this code works with width and height aligned to compressed
blocks, but at the 2x2 and 1x1 levels of a square texture (or height <
bh in general), we were skipping uploading our single row of blocks.

Fixes piglit compressedteximage GL_COMPRESSED_RGBA_S3TC_DXT5_EXT.

Reviewed-by: Brian Paul <brianp@vmware.com>

src/mesa/main/texstore.c

@@ -5139,7 +5139,7 @@ _mesa_store_compressed_texsubimage2d(struct gl_context *ctx, GLenum target,
 
    if (dstMap) {
       bytesPerRow = srcRowStride;  /* bytes per row of blocks */
-      rows = height / bh;  /* rows in blocks */
+      rows = (height + bh - 1) / bh;  /* rows in blocks */
 
       /* copy rows of blocks */
       for (i = 0; i < rows; i++) {