Disable using -fsanitize=leak from the Clang Driver.

LeakSanitizer (LSan) is not yet mature for Darwin so until this
changes we should avoid supporting it in Swift Clang and AppleClang.

rdar://problem/45841334

Author: danliew-apple

lib/Driver/ToolChains/Darwin.cpp

@@ -2358,6 +2358,9 @@ SanitizerMask Darwin::getSupportedSanitizers() const {
   Res |= SanitizerKind::FuzzerNoLink;
   Res |= SanitizerKind::Function;
 
+  // Apple-Clang: Don't support LSan. rdar://problem/45841334
+  Res &= ~SanitizerKind::Leak;
+
   // Prior to 10.9, macOS shipped a version of the C++ standard library without
   // C++11 support. The same is true of iOS prior to version 5. These OS'es are
   // incompatible with -fsanitize=vptr.

test/Driver/apple-clang-no-lsan.c

@@ -0,0 +1,7 @@
+// Apple-internal: Don't support LSan
+// REQUIRES: system-darwin
+// RUN: not %clang -fsanitize=leak %s -o %t 2>&1 | FileCheck %s
+// CHECK: unsupported option '-fsanitize=leak'
+int main() {
+  return 0;
+}

test/Driver/fsanitize.c

@@ -551,25 +551,25 @@
 // CHECK-ESAN-OPENBSD: error: unsupported option '-fsanitize=efficiency-{{.*}}' for target 'i386-pc-openbsd'
 
 // RUN: %clang -target x86_64-apple-darwin -fsanitize=leak %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-LSAN-X86-64-DARWIN
-// CHECK-LSAN-X86-64-DARWIN-NOT: unsupported option
+// CHECK-LSAN-X86-64-DARWIN: unsupported option
 
 // RUN: %clang -target x86_64-apple-iossimulator -fsanitize=leak %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-LSAN-X86-64-IOSSIMULATOR
-// CHECK-LSAN-X86-64-IOSSIMULATOR-NOT: unsupported option
+// CHECK-LSAN-X86-64-IOSSIMULATOR: unsupported option
 
 // RUN: %clang -target x86_64-apple-tvossimulator -fsanitize=leak %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-LSAN-X86-64-TVOSSIMULATOR
-// CHECK-LSAN-X86-64-TVOSSIMULATOR-NOT: unsupported option
+// CHECK-LSAN-X86-64-TVOSSIMULATOR: unsupported option
 
 // RUN: %clang -target i386-apple-darwin -fsanitize=leak %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-LSAN-I386-DARWIN
-// CHECK-LSAN-I386-DARWIN-NOT: unsupported option
+// CHECK-LSAN-I386-DARWIN: unsupported option
 
 // RUN: %clang -target arm-apple-ios -fsanitize=leak %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-LSAN-ARM-IOS
-// CHECK-LSAN-ARM-IOS-NOT: unsupported option
+// CHECK-LSAN-ARM-IOS: unsupported option
 
 // RUN: %clang -target i386-apple-iossimulator -fsanitize=leak %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-LSAN-I386-IOSSIMULATOR
-// CHECK-LSAN-I386-IOSSIMULATOR-NOT: unsupported option
+// CHECK-LSAN-I386-IOSSIMULATOR: unsupported option
 
 // RUN: %clang -target i386-apple-tvossimulator -fsanitize=leak %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-LSAN-I386-TVOSSIMULATOR
-// CHECK-LSAN-I386-TVOSSIMULATOR-NOT: unsupported option
+// CHECK-LSAN-I386-TVOSSIMULATOR: unsupported option
 
 // RUN: %clang -target i686-linux-gnu -fsanitize=efficiency-cache-frag %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-ESAN-X86
 // RUN: %clang -target i686-linux-gnu -fsanitize=efficiency-working-set %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-ESAN-X86

test/Driver/sanitizer-ld.c

@@ -537,14 +537,13 @@
 // CHECK-ASAN-DARWIN106-CXX: libclang_rt.asan_osx_dynamic.dylib
 // CHECK-ASAN-DARWIN106-CXX-NOT: -lc++abi
 
+// Apple-internal: Don't support LSan
 // RUN: %clangxx -fsanitize=leak %s -### -o %t.o 2>&1 \
 // RUN:     -mmacosx-version-min=10.6 \
 // RUN:     -target x86_64-apple-darwin13.4.0 -fuse-ld=ld -stdlib=platform \
 // RUN:     --sysroot=%S/Inputs/basic_linux_tree \
 // RUN:   | FileCheck --check-prefix=CHECK-LSAN-DARWIN106-CXX %s
-// CHECK-LSAN-DARWIN106-CXX: "{{.*}}ld{{(.exe)?}}"
-// CHECK-LSAN-DARWIN106-CXX: libclang_rt.lsan_osx_dynamic.dylib
-// CHECK-LSAN-DARWIN106-CXX-NOT: -lc++abi
+// CHECK-LSAN-DARWIN106-CXX: unsupported option '-fsanitize=leak'
 
 // RUN: %clang -no-canonical-prefixes %s -### -o %t.o 2>&1 \
 // RUN:     -target x86_64-unknown-linux -fuse-ld=ld -fsanitize=safe-stack \