gdb/testsuite/gdb.trace: Deduplicate set_point assembly.

gdb/testsuite/gdb.trace: Deduplicate set_point assembly.

The assembly code for emitting the proper tracepointable instruction
was duplicated in many places.  Keep it in one place, to reduce work
needed for new targets.

gdb/testsuite/ChangeLog:

	* gdb.trace/change-loc.h: include "trace-common.h", remove SYMBOL
	macro.
	(func5): Removed.
	(func4): Use FAST_TRACEPOINT_LABEL.
	* gdb.trace/ftrace-lock.c: include "trace-common.h", remove SYMBOL
	macro.
	(func): Removed.
	(thread_function): Use FAST_TRACEPOINT_LABEL.
	* gdb.trace/ftrace.c: include "trace-common.h", remove SYMBOL macro.
	(func): Remove.
	(marker): Use FAST_TRACEPOINT_LABEL.
	* gdb.trace/pendshr1.c: include "trace-common.h", remove SYMBOL macro.
	(pendfunc1): Remove.
	(pendfunc): Use FAST_TRACEPOINT_LABEL.
	* gdb.trace/pendshr2.c: include "trace-common.h", remove SYMBOL macro.
	(foo): Remove.
	(pendfunc2): Use FAST_TRACEPOINT_LABEL.
	* gdb.trace/trace-break.c: include "trace-common.h", remove SYMBOL
	macro.
	(func): Remove.
	(marker): Use FAST_TRACEPOINT_LABEL.
	* gdb.trace/trace-common.h: New header.
	* gdb.trace/trace-condition.c: include "trace-common.h", remove SYMBOL
	macro.
	(func): Remove.
	(marker): Use FAST_TRACEPOINT_LABEL.
	* gdb.trace/trace-mt.c: include "trace-common.h", remove SYMBOL macro.
	(func): Remove.
	(thread_function): Use FAST_TRACEPOINT_LABEL.