Process record: Fix arm-linux syscall arguments

Process record: Fix arm-linux syscall arguments

Arguments are passed in r0-r6 on arm linux syscall (both EABI and OABI).
This patch is to set arm_linux_record_tdep.arg{1-7} to the right
register number.

This patch fixes the following test failures...

-FAIL: gdb.reverse/getresuid-reverse.exp: check ruid record
-FAIL: gdb.reverse/getresuid-reverse.exp: check rgid record
-FAIL: gdb.reverse/pipe-reverse.exp: check pipe record
-FAIL: gdb.reverse/readv-reverse.exp: check readv record
-FAIL: gdb.reverse/readv-reverse.exp: check readv record
-FAIL: gdb.reverse/readv-reverse.exp: check readv record
-FAIL: gdb.reverse/readv-reverse.exp: check readv record
-FAIL: gdb.reverse/waitpid-reverse.exp: check waitpid record

gdb:

2016-03-16  Yao Qi  <yao.qi@linaro.org>

	* arm-linux-tdep.c (arm_linux_init_abi): Fix
	arm_linux_record_tdep.arg1, arm_linux_record_tdep.arg2 and
	arm_linux_record_tdep.arg3.  Set arm_linux_record_tdep.arg4,
	arm_linux_record_tdep.arg5, arm_linux_record_tdep.arg6, and
	arm_linux_record_tdep.arg7.