[Driver] Use WebAssembly toolchain for WASI target

The toolchain was introduced in 710816d
but was not used. Test cases now use fake resource dir to lookup
static-executable-args.lnk file, which is required by the toolchain but
is not present when not building stdlib for WASI.

Author: kateinoigakukun

lib/Driver/Driver.cpp

@@ -375,7 +375,7 @@ Driver::buildToolChain(const llvm::opt::InputArgList &ArgList) {
   case llvm::Triple::Haiku:
     return std::make_unique<toolchains::GenericUnix>(*this, target);
   case llvm::Triple::WASI:
-    return std::make_unique<toolchains::GenericUnix>(*this, target);
+    return std::make_unique<toolchains::WebAssembly>(*this, target);
   case llvm::Triple::UnknownOS:
     return std::make_unique<toolchains::GenericUnix>(*this, target);
   default:

test/Driver/Inputs/fake-resource-dir/lib/swift_static/wasi/static-executable-args.lnk

@@ -20,7 +20,7 @@
 // RUN: %swiftc_driver -sdk "" -driver-print-jobs -profile-generate -target x86_64-unknown-linux-gnu %s | %FileCheck -check-prefix=CHECK -check-prefix=LINUX %s
 // RUN: %swiftc_driver -sdk "" -driver-print-jobs -profile-generate -target x86_64-unknown-windows-msvc %s | %FileCheck -check-prefix=CHECK -check-prefix=WINDOWS %s
 
-// RUN: %swiftc_driver -sdk "" -driver-print-jobs -profile-generate -target wasm32-unknown-wasi %s | %FileCheck -check-prefix CHECK -check-prefix WASI %s
+// RUN: %swiftc_driver -sdk "" -driver-print-jobs -profile-generate -target wasm32-unknown-wasi -resource-dir %S/Inputs/fake-resource-dir/lib/swift_static %s | %FileCheck -check-prefix CHECK -check-prefix WASI %s
 
 // CHECK: swift
 // CHECK: -profile-generate
@@ -55,7 +55,7 @@
 // WINDOWS: -lclang_rt.profile
 
 // WASI: clang{{(\.exe)?"? }}
-// WASI: lib{{(\\\\|/)}}swift{{(\\\\|/)}}clang{{(\\\\|/)}}lib{{(\\\\|/)}}wasi{{(\\\\|/)}}libclang_rt.profile-wasm32.a
+// WASI: lib{{(\\\\|/)}}{{swift|swift_static}}{{(\\\\|/)}}clang{{(\\\\|/)}}lib{{(\\\\|/)}}wasi{{(\\\\|/)}}libclang_rt.profile-wasm32.a
 // WASI: -u__llvm_profile_runtime
 
 // RUN: not %swiftc_driver -sdk "" -driver-print-jobs -profile-generate -profile-use=/dev/null %s 2>&1 | %FileCheck -check-prefix=MIX_GEN_USE %s

test/Driver/profiling.swift

@@ -2,7 +2,7 @@
 // RUN: %swiftc_driver -driver-print-jobs -target x86_64-unknown-linux-gnu    -g -sdk %S/../Inputs/clang-importer-sdk %s 2>&1 | %FileCheck %s --check-prefix LINUX
 // RUN: %swiftc_driver -driver-print-jobs -target x86_64-unknown-freebsd      -g -sdk %S/../Inputs/clang-importer-sdk %s 2>&1 | %FileCheck %s --check-prefix FREEBSD
 // RUN: %swiftc_driver -driver-print-jobs -target x86_64-unknown-windows-msvc -g -sdk %S/../Inputs/clang-importer-sdk %s 2>&1 | %FileCheck %s --check-prefix WINDOWS
-// RUN: %swiftc_driver -driver-print-jobs -target wasm32-unknown-wasi         -g -sdk %S/../Inputs/clang-importer-sdk %s 2>&1 | %FileCheck %s --check-prefix WASI
+// RUN: %swiftc_driver -driver-print-jobs -target wasm32-unknown-wasi         -g -sdk %S/../Inputs/clang-importer-sdk -resource-dir %S/Inputs/fake-resource-dir/lib/swift_static %s 2>&1 | %FileCheck %s --check-prefix WASI
 
 // RUN: env SDKROOT=%S/../Inputs/clang-importer-sdk %swiftc_driver_plain -target x86_64-apple-macosx10.9  -g -driver-print-jobs %s 2>&1 | %FileCheck %s --check-prefix OSX
 // RUN: env SDKROOT=%S/../Inputs/clang-importer-sdk %swiftc_driver_plain -target x86_64-unknown-linux-gnu -g -driver-print-jobs %s 2>&1 | %FileCheck %s --check-prefix LINUX

test/Driver/sdk.swift

@@ -1,4 +1,4 @@
-// RUN: %swiftc_driver -driver-print-jobs -target wasm32-unknown-wasi -v %s 2>&1 | %FileCheck %s -check-prefix=CHECK-WASM
+// RUN: %swiftc_driver -driver-print-jobs -target wasm32-unknown-wasi -resource-dir %S/Inputs/fake-resource-dir/lib/swift_static -v %s 2>&1 | %FileCheck %s -check-prefix=CHECK-WASM
 
 // CHECK-WASM: swift{{.*}} -frontend -c -primary-file {{.*}} -target wasm32-unknown-wasi -disable-objc-interop
-// CHECK-WASM: clang{{.*}} -lswiftCore --target=wasm32-unknown-wasi -v {{.*}}-o
+// CHECK-WASM: clang{{.*}} -target wasm32-unknown-wasi {{.*}}static-executable-args.lnk{{.*}}-v {{.*}}-o