Remove unnecessary arbitrary CollapseFullPath second arguments

Some calls to CollapseFullPath that already have an absolute path were
updated by commit 22f38c0d6b (cmake: avoid getcwd in `CollapseFullPath`,
2020-01-14, v3.17.0-rc1~171^2) to pass an arbitrary second argument to
prevent unnecessary `getcwd` calls.  Since then, the KWSys
implementation of CollapseFullPath has learned to avoid unnecessary
`getcwd` calls on its own, so we can drop the arbitrary second arguments
to our CollapseFullPath calls.

Source/cmAddCustomCommandCommand.cxx

@@ -215,8 +215,7 @@ bool cmAddCustomCommandCommand(std::vector<std::string> const& args,
       }
 
       if (cmSystemTools::FileIsFullPath(filename)) {
-        filename = cmSystemTools::CollapseFullPath(
-          filename, status.GetMakefile().GetHomeOutputDirectory());
+        filename = cmSystemTools::CollapseFullPath(filename);
       }
       switch (doing) {
         case doing_depfile:

Source/cmCustomCommandGenerator.cxx

@@ -35,8 +35,7 @@ void AppendPaths(const std::vector<std::string>& inputs,
     for (std::string& it : result) {
       cmSystemTools::ConvertToUnixSlashes(it);
       if (cmSystemTools::FileIsFullPath(it)) {
-        it = cmSystemTools::CollapseFullPath(
-          it, lg->GetMakefile()->GetHomeOutputDirectory());
+        it = cmSystemTools::CollapseFullPath(it);
       }
     }
     cm::append(output, result);

Source/cmSourceFileLocation.cxx

@@ -33,8 +33,7 @@ cmSourceFileLocation::cmSourceFileLocation(cmMakefile const* mf,
   this->AmbiguousExtension = true;
   this->Directory = cmSystemTools::GetFilenamePath(name);
   if (cmSystemTools::FileIsFullPath(this->Directory)) {
-    this->Directory = cmSystemTools::CollapseFullPath(
-      this->Directory, mf->GetHomeOutputDirectory());
+    this->Directory = cmSystemTools::CollapseFullPath(this->Directory);
   }
   this->Name = cmSystemTools::GetFilenameName(name);
   if (kind == cmSourceFileLocationKind::Known) {