Don't trace through pkill or pgrep on macOS.

csharp/tools/osx64/compiler-tracing.spec

@@ -12,3 +12,13 @@
   invoke /usr/bin/env
   prepend /usr/bin/codesign
   trace no
+/usr/bin/pkill:
+  replace yes
+  invoke /usr/bin/env
+  prepend /usr/bin/pkill
+  trace no
+/usr/bin/pgrep:
+  replace yes
+  invoke /usr/bin/env
+  prepend /usr/bin/pgrep
+  trace no