[inline asm][gcc-compatiblity] "=i" output constraint support

Ignore ‘i’,’n’,’E’,’F’ as output constraints in inline assembly (gcc compatibility)

Differential Revision: https://reviews.llvm.org/D31383

llvm-svn: 306297
diff --git a/clang/lib/Basic/TargetInfo.cpp b/clang/lib/Basic/TargetInfo.cpp
index 8cfd8bd..4bcebad 100644
--- a/clang/lib/Basic/TargetInfo.cpp
+++ b/clang/lib/Basic/TargetInfo.cpp
@@ -507,6 +507,11 @@
     case '?': // Disparage slightly code.
     case '!': // Disparage severely.
     case '*': // Ignore for choosing register preferences.
+    case 'i': // Ignore i,n,E,F as output constraints (match from the other
+              // chars)
+    case 'n':
+    case 'E':
+    case 'F':
       break;  // Pass them.
     }