StringUtils: use the locale-unaware tolower function

There is no change in behaviour since we were using the C locale.

The locale-aware tolower is much slower than the locale-unaware one. At least on Linux/GCC it calls dynamic_cast's, and is overall slower by an order of magnitude.

components/misc/stringops.hpp

@@ -4,18 +4,15 @@
 #include <cctype>
 #include <string>
 #include <algorithm>
-#include <locale>
 
 namespace Misc
 {
 class StringUtils
 {
-
-    static std::locale mLocale;
     struct ci
     {
         bool operator()(char x, char y) const {
-            return std::tolower(x, StringUtils::mLocale) < std::tolower(y, StringUtils::mLocale);
+            return tolower(x) < tolower(y);
         }
     };
 
@@ -31,7 +28,7 @@ class StringUtils
         std::string::const_iterator xit = x.begin();
         std::string::const_iterator yit = y.begin();
         for (; xit != x.end(); ++xit, ++yit) {
-            if (std::tolower(*xit, mLocale) != std::tolower(*yit, mLocale)) {
+            if (tolower(*xit) != tolower(*yit)) {
                 return false;
             }
         }
@@ -45,7 +42,7 @@ class StringUtils
         for(;xit != x.end() && yit != y.end() && len > 0;++xit,++yit,--len)
         {
             int res = *xit - *yit;
-            if(res != 0 && std::tolower(*xit, mLocale) != std::tolower(*yit, mLocale))
+            if(res != 0 && tolower(*xit) != tolower(*yit))
                 return (res > 0) ? 1 : -1;
         }
         if(len > 0)
@@ -61,7 +58,7 @@ class StringUtils
     /// Transforms input string to lower case w/o copy
     static std::string &toLower(std::string &inout) {
         for (unsigned int i=0; i<inout.size(); ++i)
-            inout[i] = std::tolower(inout[i], mLocale);
+            inout[i] = tolower(inout[i]);
         return inout;
     }