Read corrrect auxiliary entry in AIX

Read corrrect auxiliary entry in AIX

Fix handling of XCOFF function auxiliary entries, in particular when
the xlc -qfuncsect or gcc -ffunction-sections compiler option is used
in AIX.  Also handle C_WEAKEXT storage class.

gdb/
2016-10-21  Sangamesh Mallayya  <sangamesh.swamy@in.ibm.com>
	    Ulrich Weigand  <uweigand@de.ibm.com>

	* xcoffread.c (read_xcoff_symtab): Read correct function auxiliary
	entry if xlc -qfuncsect or gcc -ffunction-sections compiler option
	is used in AIX.
	(read_xcoff_symtab): Handle C_WEAKEXT storage class.
	(process_xcoff_symbol): Likewise.
	(scan_xcoff_symtab): Likewise.

Signed-off-by: Ulrich Weigand <ulrich.weigand@de.ibm.com>