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/cmForEachCommand.cxx b/Source/cmForEachCommand.cxx
index df288bd..9ff967c 100644
--- a/Source/cmForEachCommand.cxx
+++ b/Source/cmForEachCommand.cxx
@@ -29,10 +29,10 @@ bool cmForEachFunctionBlocker::IsFunctionBlocked(const cmListFileFunction& lff,
                                                  cmMakefile& mf,
                                                  cmExecutionStatus& inStatus)
 {
-  if (!cmSystemTools::Strucmp(lff.Name.c_str(), "foreach")) {
+  if (lff.Name.Lower == "foreach") {
     // record the number of nested foreach commands
     this->Depth++;
-  } else if (!cmSystemTools::Strucmp(lff.Name.c_str(), "endforeach")) {
+  } else if (lff.Name.Lower == "endforeach") {
     // if this is the endofreach for this statement
     if (!this->Depth) {
       // Remove the function blocker for this scope or bail.
@@ -97,7 +97,7 @@ bool cmForEachFunctionBlocker::IsFunctionBlocked(const cmListFileFunction& lff,
 bool cmForEachFunctionBlocker::ShouldRemove(const cmListFileFunction& lff,
                                             cmMakefile& mf)
 {
-  if (!cmSystemTools::Strucmp(lff.Name.c_str(), "endforeach")) {
+  if (lff.Name.Lower == "endforeach") {
     std::vector<std::string> expandedArguments;
     mf.ExpandArguments(lff.Arguments, expandedArguments);
     // if the endforeach has arguments then make sure