Make armv6 iOS by default instead of macOS when targeting Darwin (#117243)

AFAIK the only publicly released armv6 devices that ran Darwin were the
iPhone 2G, iPhone 3G, iPod touch 1, and the iPod touch 2, all of which
were iOS devices.

Author: Un1q32

clang/lib/Driver/ToolChains/Darwin.cpp

@@ -2164,7 +2164,8 @@ inferDeploymentTargetFromArch(DerivedArgList &Args, const Darwin &Toolchain,
   StringRef MachOArchName = Toolchain.getMachOArchName(Args);
   if (MachOArchName == "arm64" || MachOArchName == "arm64e")
     OSTy = llvm::Triple::MacOSX;
-  else if (MachOArchName == "armv7" || MachOArchName == "armv7s")
+  else if (MachOArchName == "armv7" || MachOArchName == "armv7s" ||
+           MachOArchName == "armv6")
     OSTy = llvm::Triple::IOS;
   else if (MachOArchName == "armv7k" || MachOArchName == "arm64_32")
     OSTy = llvm::Triple::WatchOS;

clang/test/Driver/darwin-version.c

@@ -1,6 +1,6 @@
 // RUN: %clang -target armv6-apple-darwin9 -c %s -### 2>&1 | \
-// RUN:   FileCheck --check-prefix=CHECK-VERSION-OSX %s
-// CHECK-VERSION-OSX: "armv6k-apple-macosx10.5.0"
+// RUN:   FileCheck --check-prefix=CHECK-VERSION-IOS %s
+// CHECK-VERSION-IOS: "armv6k-apple-ios5.0.0"
 // RUN: %clang -target armv6-apple-darwin9 -miphoneos-version-min=2.0 -c %s -### 2>&1 | \
 // RUN:   FileCheck --check-prefix=CHECK-VERSION-IOS2 %s
 // CHECK-VERSION-IOS2: "armv6k-apple-ios2.0.0"