Fix compile error on Windows after WL#1054 push.

The error was introduced by typo in variable name (errormsg instead of correct
errmsg)

- Also, precache  HAVE_PEERCRED to OFF in cmake\os\WindowsCache.cmake
(to avoid useless system check).
- Also, add missing check for errors from FormatMessage().

- Also, remove annoying CMake debug printout of MALLOC_LIB if this is not set.

cmake/os/WindowsCache.cmake

@@ -131,6 +131,7 @@ SET(HAVE_PASE_ENVIRONMENT CACHE  INTERNAL "")
 SET(HAVE_PATHS_H CACHE  INTERNAL "")
 SET(HAVE_PCLOSE CACHE  INTERNAL "")
 SET(HAVE_PERROR 1 CACHE  INTERNAL "")
+SET(HAVE_PEERCRED CACHE INTERNAL "")
 SET(HAVE_POLL_H CACHE  INTERNAL "")
 SET(HAVE_POPEN CACHE  INTERNAL "")
 SET(HAVE_POLL CACHE INTERNAL "")

scripts/CMakeLists.txt

@@ -84,8 +84,6 @@ INSTALL(FILES
 IF(MALLOC_LIB)
   MESSAGE("Using tcmalloc '${MALLOC_LIB}'")
   INSTALL(FILES ${MALLOC_LIB} DESTINATION ${INSTALL_LIBDIR} OPTIONAL)
-ELSE()
-  MESSAGE("No 'MALLOC_LIB' variable")
 ENDIF()
 
 IF(CMAKE_GENERATOR MATCHES "Makefiles")

sql-common/client_plugin.c

@@ -322,7 +322,7 @@ mysql_load_plugin_v(MYSQL *mysql, const char *name, int type,
   char dlpath[FN_REFLEN+1];
   void *sym, *dlhandle;
   struct st_mysql_client_plugin *plugin;
-#ifdef WIN32
+#ifdef _WIN32
   char win_errormsg[2048];
 #endif
 
@@ -364,10 +364,12 @@ mysql_load_plugin_v(MYSQL *mysql, const char *name, int type,
 #endif
 
     DBUG_PRINT ("info", ("failed to dlopen"));
-#ifdef WIN32
-    FormatMessage(FORMAT_MESSAGE_FROM_SYSTEM,
-                  0, GetLastError(), 0, win_errormsg, 2048, NULL);
-    errormsg= win_errormsg;
+#ifdef _WIN32
+    if(FormatMessage(FORMAT_MESSAGE_FROM_SYSTEM,
+                  0, GetLastError(), 0, win_errormsg, 2048, NULL))
+      errmsg= win_errormsg;
+    else
+      errmsg= "";
 #else
     errmsg= dlerror();
 #endif