linux-user, arm: add syscall table generation support

Copy syscall.tbl and syscallhdr.sh from linux/arch/arm/tools/syscalls v5.5
Update syscallhdr.sh to generate QEMU syscall_nr.h

Update syscall.c to manage TARGET_NR_arm_sync_file_range as it has
replaced TARGET_NR_sync_file_range2

Move existing stuff from linux-user/Makefile.objs to
linux-user/arm/Makefile.objs

Signed-off-by: Laurent Vivier <laurent@vivier.eu>
Reviewed-by: Taylor Simpson <tsimpson@quicinc.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20200310103403.3284090-9-laurent@vivier.eu>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index e55a477..6107834 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -11830,8 +11830,14 @@
 #endif
         return ret;
 #endif
+#if defined(TARGET_NR_sync_file_range2) || \
+    defined(TARGET_NR_arm_sync_file_range)
 #if defined(TARGET_NR_sync_file_range2)
     case TARGET_NR_sync_file_range2:
+#endif
+#if defined(TARGET_NR_arm_sync_file_range)
+    case TARGET_NR_arm_sync_file_range:
+#endif
         /* This is like sync_file_range but the arguments are reordered */
 #if TARGET_ABI_BITS == 32
         ret = get_errno(sync_file_range(arg1, target_offset64(arg3, arg4),