u-boot: fix extern inline build errors for gcc 5
The gcc 5 change its default standard from gnu89 to gnu11. These two
standards do have different semantics for inline functions. And the
gcc 5 will emit the following errors on the "extern inline" functions:
arch/powerpc/cpu/mpc8xxx/fsl_lbc.o: In function `ld_le16':
./arch/powerpc/include/asm/byteorder.h:12: multiple definition of `ld_le16'
arch/powerpc/cpu/mpc8xxx/fdt.o:./arch/powerpc/include/asm/byteorder.h:12: first defined here
Fix these build errors by using "-fgnu89-inline" to enforce the gnu89
inline semantics as suggested in [1].
[1] https://gcc.gnu.org/gcc-5/porting_to.html
(From OE-Core rev:
a1c83bb5556837d31d934b9af130cdbac19d5e97)
Signed-off-by: Kevin Hao <kexin.hao@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
Signed-off-by: Joshua Lock <joshua.lock@collabora.co.uk>
