[gn] Remove ScudoBenchmarks

It's the only thing depending on third-party/benchmark.
The recent third-party/benchmark uprev made it not build in the
GN build, so remove ScudoBenchmarks until someone feels motivated
to update the third-party/benchmark BUILD.gn file.

Author: nico

llvm/utils/gn/secondary/compiler-rt/lib/scudo/BUILD.gn

@@ -11,7 +11,6 @@ group("scudo") {
   deps = []
   foreach(toolchain, supported_toolchains) {
     deps += [
-      "standalone/benchmarks:ScudoBenchmarks($toolchain)",
       "standalone/tests:ScudoCUnitTest($toolchain)",
       "standalone/tests:ScudoCxxUnitTest($toolchain)",
       "standalone/tests:ScudoHooksUnitTest($toolchain)",