Use SWIFT_BUILD_SWIFT_SYNTAX instead of SWIFT_SWIFT_PARSER

Author: DougGregor

lib/Parse/Lexer.cpp

@@ -35,7 +35,7 @@
 // Regex lexing delivered via libSwift.
 static RegexLiteralLexingFn regexLiteralLexingFn = nullptr;
 
-#if SWIFT_SWIFT_PARSER
+#if SWIFT_BUILD_SWIFT_SYNTAX
 void Parser_registerRegexLiteralLexingFn(RegexLiteralLexingFn fn) {
   regexLiteralLexingFn = fn;
 }

lib/Parse/ParseRegex.cpp

@@ -21,7 +21,7 @@
 // Regex parser delivered via Swift modules.
 static RegexLiteralParsingFn regexLiteralParsingFn = nullptr;
 
-#if SWIFT_SWIFT_PARSER
+#if SWIFT_BUILD_SWIFT_SYNTAX
 void Parser_registerRegexLiteralParsingFn(RegexLiteralParsingFn fn) {
   regexLiteralParsingFn = fn;
 }