[Fuzzer][Test-Only][Darwin] Mark coverage.test and exit_on_src_pos.test unsupported (llvm#165408)

These tests are currently failing on some CI macOS instances due to an
issue with the system symbolizer.

This patch marks the tests unsupported on Darwin while we wait for all
CI machines to be updated to a newer OS.

rdar://160410051

Author: DanBlackwell

compiler-rt/test/fuzzer/coverage.test

@@ -2,6 +2,8 @@
 UNSUPPORTED: target={{.*windows.*}}
 # FIXME: CreatePCArray() emits PLT stub addresses for entry blocks, which are ignored by TracePC::PrintCoverage().
 UNSUPPORTED: target=s390x{{.*}}
+UNSUPPORTED: darwin
+
 RUN: mkdir -p %t.dir && cd %t.dir
 RUN: %cpp_compiler -mllvm -use-unknown-locations=Disable  %S/NullDerefTest.cpp -o %t.dir/NullDerefTest
 RUN: %cpp_compiler -mllvm -use-unknown-locations=Disable %S/DSO1.cpp -fPIC %ld_flags_rpath_so1 -O0 -shared -o %dynamiclib1

compiler-rt/test/fuzzer/exit_on_src_pos.test

@@ -8,6 +8,7 @@
 UNSUPPORTED: target=thumb{{.*}}
 # Timeout on loongarch64 machine
 UNSUPPORTED: target=loongarch64{{.*}}
+UNSUPPORTED: darwin
 
 RUN: %cpp_compiler -O0 %S/SimpleTest.cpp -o %t-SimpleTest.exe -mllvm -use-unknown-locations=Disable
 RUN: %cpp_compiler -O0 %S/ShrinkControlFlowTest.cpp -o %t-ShrinkControlFlowTest.exe