Style print_address_symbolic

Style print_address_symbolic

print_address_symbolic does not use ui-out, so it did not style
function names.  This patch changes it to use the low-level style code
directly.

gdb/ChangeLog
2018-12-28  Tom Tromey  <tom@tromey.com>

	* printcmd.c (print_address_symbolic): Style function name.

gdb/testsuite/ChangeLog
2018-12-28  Tom Tromey  <tom@tromey.com>

	* gdb.base/style.exp: Add test for print_address_symbolic.