Remove temporary allocations when calling cmHasLiteral{Suf,Pre}fix.

When the first argument passed is a std::string, we need to take it
by const&, otherwise we copy the string and trigger a temporary
allocation. This patch removes a few 10k temporary allocations when
running the CMake daemon on the KDevelop build dir.

This hotspot was found with heaptrack.

Source/cmAlgorithms.h

@@ -52,13 +52,13 @@ template<typename T, size_t N>
 size_t cmArraySize(const T (&)[N]) { return N; }
 
 template<typename T, size_t N>
-bool cmHasLiteralPrefix(T str1, const char (&str2)[N])
+bool cmHasLiteralPrefix(const T& str1, const char (&str2)[N])
 {
   return cmHasLiteralPrefixImpl(str1, str2, N - 1);
 }
 
 template<typename T, size_t N>
-bool cmHasLiteralSuffix(T str1, const char (&str2)[N])
+bool cmHasLiteralSuffix(const T& str1, const char (&str2)[N])
 {
   return cmHasLiteralSuffixImpl(str1, str2, N - 1);
 }