test: use llvm tools

Rather than relying on the system to provide ar and nm, use the LLVM equivalent
tools instead.  Since the build is already dependent on llvm and its tools, this
just ensures that the full set is self-contained.  NFC.

Author: compnerd

test/AutolinkExtract/empty_archive.swift

@@ -1,6 +1,6 @@
 // RUN: %target-swiftc_driver -c %s -o %t
 // RUN: rm -f %t.a
-// RUN: ar cr %t.a %t
+// RUN: llvm-ar cr %t.a %t
 // RUN: %target-swift-autolink-extract %t.a -o - | FileCheck --check-prefix CHECK-%target-object-format %s
 
 // REQUIRES: autolink-extract

test/AutolinkExtract/import_archive.swift

@@ -2,7 +2,7 @@
 // RUN: mkdir -p %t
 // RUN: %target-swiftc_driver -emit-library -emit-module -emit-module-path %t/empty.swiftmodule -module-name empty -module-link-name empty %S/empty.swift
 // RUN: %target-swiftc_driver -c %s -I %t -o %t/import_experimental.o
-// RUN: ar cr %t/import_experimental.a %t/import_experimental.o
+// RUN: llvm-ar cr %t/import_experimental.a %t/import_experimental.o
 // RUN: %target-swift-autolink-extract %t/import_experimental.a -o - | FileCheck --check-prefix CHECK-%target-object-format %s
 
 // REQUIRES: autolink-extract

test/multifile/protocol-conformance-member.swift

@@ -1,6 +1,6 @@
 // RUN: rm -rf %t && mkdir %t
 // RUN: %target-build-swift -emit-library %s %S/Inputs/protocol-conformance-member-helper.swift -o %t/libTest.dylib -module-name Test
-// RUN: nm %t/libTest.dylib | FileCheck %s
+// RUN: llvm-nm %t/libTest.dylib | FileCheck %s
 
 // CHECK: _TFV4Test10CoolStructg10coolFactorSd