testsuite: disable T367_letnoescape on 'optllvm'

Known Issue #7297
Signed-off-by: Sergei Trofimovich <slyfox@gentoo.org>

testsuite/tests/concurrent/should_run/all.T

@@ -23,7 +23,7 @@ test('conc073', normal, compile_and_run, [''])
 
 # vector code must get inlined to become non-allocating
 test('T367', [reqlib('vector'), omit_ways(['ghci']), timeout_multiplier(0.001)], compile_and_run, ['-O2 -fno-omit-yields'])
-test('T367_letnoescape', [timeout_multiplier(0.02)], compile_and_run, ['-fno-omit-yields'])
+test('T367_letnoescape', [timeout_multiplier(0.02), expect_broken_for(7297,['optllvm'])], compile_and_run, ['-fno-omit-yields'])
 
 test('T1980', normal, compile_and_run, [''])
 test('T2910', normal, compile_and_run, [''])