GCC 3.1 changes

llvm-svn: 3074
diff --git a/llvm/lib/AsmParser/Lexer.l b/llvm/lib/AsmParser/Lexer.l
index faddcb1..b837325 100644
--- a/llvm/lib/AsmParser/Lexer.l
+++ b/llvm/lib/AsmParser/Lexer.l
@@ -85,7 +85,7 @@
 // If AllowNull is set to true, the return value of the function points to the
 // last character of the string in memory.
 //
-char *UnEscapeLexed(char *Buffer, bool AllowNull = false) {
+char *UnEscapeLexed(char *Buffer, bool AllowNull) {
   char *BOut = Buffer;
   for (char *BIn = Buffer; *BIn; ) {
     if (BIn[0] == '\\' && isxdigit(BIn[1]) && isxdigit(BIn[2])) {