Use load_windows_system_library in place of LoadLibrary

changes/bug1954_loadlib

@@ -0,0 +1,4 @@
+  o Major bugfixes
+    - Always search the windows system directory for system DLLs, and
+      nowhere else.  Fixes bug 1954.
+

src/or/eventdns.c

@@ -3132,7 +3132,7 @@ load_nameservers_with_getnetworkparams(void)
 	GetNetworkParams_fn_t fn;
 
 	/* XXXX Possibly, we should hardcode the location of this DLL. */
-	if (!(handle = LoadLibrary(TEXT("iphlpapi.dll")))) {
+	if (!(handle = load_windows_system_library(TEXT("iphlpapi.dll")))) {
 		log(EVDNS_LOG_WARN, "Could not open iphlpapi.dll");
 		/* right now status = 0, doesn't that mean "good" - mikec */
 		status = -1;

src/or/ntmain.c

@@ -139,7 +139,7 @@ nt_service_loadlibrary(void)
     return;
 
   /* XXXX Possibly, we should hardcode the location of this DLL. */
-  if (!(library = LoadLibrary(TEXT("advapi32.dll")))) {
+  if (!(library = load_windows_system_library(TEXT("advapi32.dll")))) {
     log_err(LD_GENERAL, "Couldn't open advapi32.dll.  Are you trying to use "
             "NT services on Windows 98? That doesn't work.");
     goto err;