Use the integrated assembler as default on PowerPC

This was already done in clang, this commit now uses the integrated
assembler as default when using LLVM tools directly.

A number of test cases using inline asm had to be adapted, either by
updating the expected output, or by using -no-integrated-as (for such
tests that deliberately use an invalid instruction in inline asm).

llvm-svn: 225819
diff --git a/llvm/test/CodeGen/PowerPC/ia-neg-const.ll b/llvm/test/CodeGen/PowerPC/ia-neg-const.ll
index 165fc13..556ab80 100644
--- a/llvm/test/CodeGen/PowerPC/ia-neg-const.ll
+++ b/llvm/test/CodeGen/PowerPC/ia-neg-const.ll
@@ -14,8 +14,8 @@
 }
 
 ; CHECK: ld
-; CHECK-NOT: addi   3,3,4294967295
-; CHECK: addi   3,3,-1
+; CHECK-NOT: addi   3, 3, 4294967295
+; CHECK: addi   3, 3, -1
 ; CHECK: blr
 
 ; Function Attrs: nounwind