[clang] Remove a FIXME that we can't fix

I added this recently, but it looks like several tests very intentionally
check that `-mios-version-min=foo --target=x86_64-apple-ios` does simulator
builds. So we can't easily remove this hack, even though it makes little
sense in an arm mac world. (Here, you _have_ to say
`-mios-simulator-version-min=` or `--target=arm64-apple-ios-simulator`.)

The tests that check this:
  Clang :: Driver/darwin-ld.c
  Clang :: Driver/darwin-simulator-macro.c
  Clang :: Driver/darwin-version.c

No behavior change.

Differential Revision: https://reviews.llvm.org/D132400

Author: nico

clang/lib/Driver/ToolChains/Darwin.cpp

@@ -2241,7 +2241,6 @@ void Darwin::AddDeploymentTarget(DerivedArgList &Args) const {
 
   DarwinEnvironmentKind Environment = OSTarget->getEnvironment();
   // Recognize iOS targets with an x86 architecture as the iOS simulator.
-  // FIXME: Remove this.
   if (Environment == NativeEnvironment && Platform != MacOS &&
       Platform != DriverKit && OSTarget->canInferSimulatorFromArch() &&
       getTriple().isX86())