[asan][test] Disable suppressions-alloc-dealloc-mismatch.cpp on Darwin

The suppressions mechanism doesn't work reliably in optimized builds,
which turns out to be a known issue (see b87543c / svn r308908).
Disable this test, as it is also testing a feature (alloc/dealloc
mismatch) that is disabled by default on Darwin anyway.

rdar://143830493

Author: benlangmuir

compiler-rt/test/asan/TestCases/suppressions-alloc-dealloc-mismatch.cpp

@@ -9,6 +9,10 @@
 // FIXME: Upload suppressions to device.
 // XFAIL: android
 
+// FIXME: atos does not work for inlined functions, yet llvm-symbolizer
+// does not always work with debug info on Darwin.
+// UNSUPPORTED: darwin
+
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>