cmMakefile: Let AddDefinition accept a value as cm::string_view

This changes `cmMakefile::AddDefinition` to take a `cm::string_view` as value
argument instead of a `const char *`.

Benefits are:
- `std::string` can be passed to `cmMakefile::AddDefinition` directly without
  the `c_str()` plus string length recomputation fallback.
- Lengths of literals passed to `cmMakefile::AddDefinition` can be computed at
  compile time.

In various sources uses of `cmMakefile::AddDefinition` are adapted to avoid
`std::string::c_str` calls and the `std::string` is passed directly.
Uses of `cmMakefile::AddDefinition`, where a `nullptr` `const char*` might
be passed to `cmMakefile::AddDefinition` are extended with `nullptr` checks.

1 files changed, 1 insertions, 3 deletions

diff --git a/Source/CTest/cmCTestMemCheckCommand.cxx b/Source/CTest/cmCTestMemCheckCommand.cxx
index 7dad1ce..d7d42bf 100644
--- a/Source/CTest/cmCTestMemCheckCommand.cxx
+++ b/Source/CTest/cmCTestMemCheckCommand.cxx
@@ -3,7 +3,6 @@
 #include "cmCTestMemCheckCommand.h"
 
 #include <sstream>
-#include <string>
 #include <vector>
 
 #include "cmCTest.h"
@@ -47,7 +46,6 @@ void cmCTestMemCheckCommand::ProcessAdditionalValues(
   if (this->Values[ctm_DEFECT_COUNT] && *this->Values[ctm_DEFECT_COUNT]) {
     std::ostringstream str;
     str << static_cast<cmCTestMemCheckHandler*>(handler)->GetDefectCount();
-    this->Makefile->AddDefinition(this->Values[ctm_DEFECT_COUNT],
-                                  str.str().c_str());
+    this->Makefile->AddDefinition(this->Values[ctm_DEFECT_COUNT], str.str());
   }
 }