webkitgtk: Enable building for ARC architecture

webkitgtk: Enable building for ARC architecture

For that we need 2 things:
 1. Disable JIT in JS as it's not supported for ARC.

 2. Compile with "-mlong-calls" so relocations with
    offsets larger than 25 bits are used, otherwise
    linker fails to link final binaries.

Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Cc: Alexander Kanavin <alex.kanavin@gmail.com>
Cc: Hongxu Jia <hongxu.jia@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>