[sancov][NFC] Make filename Regexes "const"

Summary:
The const-correctness of match() was fixed in rL372764, which allows
such static Regex objects to be marked const.

Reviewers: thopre

Reviewed By: thopre

Subscribers: llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D68091

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@373058 91177308-0d34-0410-b5e6-96231b3b80d8

tools/sancov/sancov.cpp

@@ -123,8 +123,8 @@ static const uint32_t BinCoverageMagic = 0xC0BFFFFF;
 static const uint32_t Bitness32 = 0xFFFFFF32;
 static const uint32_t Bitness64 = 0xFFFFFF64;
 
-static Regex SancovFileRegex("(.*)\\.[0-9]+\\.sancov");
-static Regex SymcovFileRegex(".*\\.symcov");
+static const Regex SancovFileRegex("(.*)\\.[0-9]+\\.sancov");
+static const Regex SymcovFileRegex(".*\\.symcov");
 
 // --------- MAIN DATASTRUCTURES ----------