[LTO] Require asserts for discard-value-names.ll test.

The test requires asserts, as it depends on the default value for
-lto-discard-value-names at the moment.

Author: fhahn

llvm/test/tools/lto/discard-value-names.ll

@@ -5,7 +5,12 @@
 ; RUN: %ld64 -lto_library %llvmshlibdir/libLTO.dylib -dylib -arch x86_64 -macos_version_min 10.10.0 -o %t.dylib %t.o -save-temps  -undefined dynamic_lookup -exported_symbol _bar -lSystem -mllvm -lto-discard-value-names=false
 ; RUN: llvm-dis %t.dylib.lto.opt.bc -o - | FileCheck --check-prefix=KEEP %s
 
+; The test requires asserts, as it depends on the default value for
+; -lto-discard-value-names at the moment.
 ; FIXME: -lto-discard-value-names is ignored at the moment.
+
+; REQUIRES: asserts
+
 ; DISCARD: %cmp.i = icmp
 ; DISCARD: %add = add i32