perf test: Make perf trace BTF general tests exclusive

perf test: Make perf trace BTF general tests exclusive

Running both tests cases 126 128 together causes the first test case
126 to fail:
 # for i in $(seq 3); do ./perf test 'perf trace BTF general tests' \
	'perf trace record and replay'; done
 126: perf trace BTF general tests    : FAILED!
 128: perf trace record and replay    : Ok
 126: perf trace BTF general tests    : FAILED!
 128: perf trace record and replay    : Ok
 126: perf trace BTF general tests    : FAILED!
 128: perf trace record and replay    : Ok
 #

Test case 126 fails because test case 128 runs concurrently as can
be observed using a ps -ef | grep perf output list on a different
window. Both do a perf trace command concurrently.
Make test case 'perf trace BTF general tests' exclusive.

Output after:
 # for i in $(seq 3); do ./perf test 'perf trace BTF general tests' \
	'perf trace record and replay'; done
 127: perf trace BTF general tests                   : Ok
 155: perf trace record and replay                   : Ok
 127: perf trace BTF general tests                   : Ok
 155: perf trace record and replay                   : Ok
 127: perf trace BTF general tests                   : Ok
 155: perf trace record and replay                   : Ok
 #

Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Acked-by: Howard Chu <howardchu95@gmail.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>