sh: fix LIBGCC

Commit f15cbe6f
(sh: migrate to arch/sh/include/) moved KBUILD_CFLAGS
(which is used by LIBGCC) below LIBGCC, causing build
errors like the following:

<--  snip  -->

...
  LD      .tmp_vmlinux1
arch/sh/kernel/built-in.o: In function `module_clk_recalc':
clock-sh4.c:(.text+0x80f0): undefined reference to `__udivsi3_i4i'
...
make[1]: *** [.tmp_vmlinux1] Error 1

<--  snip  -->

Reported-by: Adrian Bunk <bunk@kernel.org>
Signed-off-by: Adrian Bunk <bunk@kernel.org>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>