Revise implementation of case-insensitive command names

Store both the as-written and lower-case command names and use
the latter to avoid case-insensitive string comparisons.

With this I obtain 2-6% speed increase (on Windows) for the configure
step with no significant changes in memory usage.  A case-insensitive
comparison is a lot slower than just calling `==` because the operator
will use things like memcmp, so prefer the latter.

The `cmSystemTools::LowerCase` function allocates a new string each time
it is called, so before this change we were allocating in:

* cmMakefile::Configure two times for each function
  (to look for `cmake_minimum_required` and `project`)
* cmMakefile::ExecuteCommand twice by function by calling
  cmState::GetCommand and copying the name

Now we are only allocating once by function instead of four.

1 files changed, 3 insertions, 3 deletions

diff --git a/Source/cmWhileCommand.cxx b/Source/cmWhileCommand.cxx
index a080034..d5bcfc2 100644
--- a/Source/cmWhileCommand.cxx
+++ b/Source/cmWhileCommand.cxx
@@ -28,10 +28,10 @@ bool cmWhileFunctionBlocker::IsFunctionBlocked(const cmListFileFunction& lff,
                                                cmExecutionStatus& inStatus)
 {
   // at end of for each execute recorded commands
-  if (!cmSystemTools::Strucmp(lff.Name.c_str(), "while")) {
+  if (lff.Name.Lower == "while") {
     // record the number of while commands past this one
     this->Depth++;
-  } else if (!cmSystemTools::Strucmp(lff.Name.c_str(), "endwhile")) {
+  } else if (lff.Name.Lower == "endwhile") {
     // if this is the endwhile for this while loop then execute
     if (!this->Depth) {
       // Remove the function blocker for this scope or bail.
@@ -117,7 +117,7 @@ bool cmWhileFunctionBlocker::IsFunctionBlocked(const cmListFileFunction& lff,
 bool cmWhileFunctionBlocker::ShouldRemove(const cmListFileFunction& lff,
                                           cmMakefile&)
 {
-  if (!cmSystemTools::Strucmp(lff.Name.c_str(), "endwhile")) {
+  if (lff.Name.Lower == "endwhile") {
     // if the endwhile has arguments, then make sure
     // they match the arguments of the matching while
     if (lff.Arguments.empty() || lff.Arguments == this->Args) {