[Support] Fix a warning introduced in r280339 due to the member

initializers not being in the same order as the members.

Specifically, 'preg' is the first member followed by 'error', so they
will be initialized in that order and should be written in the member
initializer list in that order.

For the constructor in question, there is no change in behavior.

llvm-svn: 280345

llvm/lib/Support/Regex.cpp

@@ -19,7 +19,7 @@
 #include <string>
 using namespace llvm;
 
-Regex::Regex() : error(REG_BADPAT), preg(nullptr) {}
+Regex::Regex() : preg(nullptr), error(REG_BADPAT) {}
 
 Regex::Regex(StringRef regex, unsigned Flags) {
   unsigned flags = 0;