Fix two misleading indentation warnings

Fix two misleading indentation warnings

Two small changes so everything builds with latest GCC and its
-Wmisleading-indentation.

In the aarch64-tdep.c case, the two misindented lines should actually be
part of the for loop.  It looks like the indentation is all done using
spaces in that file though...  I fixed it (changed for tabs + spaces) for
the lines I touched.

In the xcoffread.c case, we can simply remove the braces and fix the
indentation.

gdb/ChangeLog:

	* aarch64-tdep.c (aarch64_record_asimd_load_store): Add braces
	to for include additional lines.
	* xcoffread.c (scan_xcoff_symtab): Remove unnecessary braces.