Add test case for tracepoints with conditions

Add test case for tracepoints with conditions

This patch adds a test case for tracepoints with a condition expression.
Each case will test a condition against the number of frames that should
have been traced.  Some of these tests fail on x86_64 and others on
i386, which have been marked as known failures for now, see PR/18955.

gdb/testsuite/ChangeLog:

2015-09-17  Pierre Langlois  <pierre.langlois@arm.com>
	    Yao Qi  <yao.qi@linaro.org>

	* gdb.trace/trace-condition.c: New file.
	* gdb.trace/trace-condition.exp: New file.