linux-user: Fix structure target_flock definition for Mips

linux-user: Fix structure target_flock definition for Mips

Structure flock is defined for Mips in a way different from any
other platform. For reference, see Linux kernel source code files:

arch/mips/include/uapi/asm/fcntl.h, line 63 (for Mips)
include/uapi/asm-generic/fcntl.h, line 195 (for all other platforms)

This patch fix this problem, by amending structure target_flock,
for Mips only.

Besides, this patch fixes LTP tests fcntl11, fcntl17, fcntl19, fcntl20,
and fcntl21, which are currently failing, if executed in Qemu user mode
for Mips platforms.

Signed-off-by: Aleksandar Markovic <aleksandar.markovic@imgtec.com>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Reviewed-by: Leon Alrae <leon.alrae@imgtec.com>
Acked-by: Riku Voipio <riku.voipio@linaro.org>
Signed-off-by: Leon Alrae <leon.alrae@imgtec.com>