Fix misleading usage of return type of Open*Log

In an earlier version of 791c887e22046e5e7a2d05ecb5ff27701d56895d those
functions returned LoadStatus, too, but it was changed back to bool.
diff --git a/src/ninja.cc b/src/ninja.cc
index 1cff6e8..56e31e0 100644
--- a/src/ninja.cc
+++ b/src/ninja.cc
@@ -136,11 +136,11 @@
   int ToolWinCodePage(const Options* options, int argc, char* argv[]);
 
   /// Open the build log.
-  /// @return LOAD_ERROR on error.
+  /// @return false on error.
   bool OpenBuildLog(bool recompact_only = false);
 
   /// Open the deps log: load it, then open for writing.
-  /// @return LOAD_ERROR on error.
+  /// @return false on error.
   bool OpenDepsLog(bool recompact_only = false);
 
   /// Ensure the build directory exists, creating it if necessary.
@@ -894,8 +894,8 @@
   if (!EnsureBuildDirExists())
     return 1;
 
-  if (OpenBuildLog(/*recompact_only=*/true) == LOAD_ERROR ||
-      OpenDepsLog(/*recompact_only=*/true) == LOAD_ERROR)
+  if (!OpenBuildLog(/*recompact_only=*/true) ||
+      !OpenDepsLog(/*recompact_only=*/true))
     return 1;
 
   return 0;