Remove run-time requirement for advapi32.dll since

c-ares can work even with no advapi32.dll at all.

ares/ares.h

@@ -96,8 +96,7 @@ extern "C" {
 
 /* ares_library_init error codes */
 #define ARES_ELOADIPHLPAPI           21
-#define ARES_ELOADADVAPI32           22
-#define ARES_EADDRGetNetworkParams   23
+#define ARES_EADDRGetNetworkParams   22
 
 /* Flag values */
 #define ARES_FLAG_USEVC         (1 << 0)

ares/ares_library_init.c

@@ -41,23 +41,20 @@ static int ares_win32_init(void)
       return ARES_EADDRGetNetworkParams;
     }
 
+  /*
+   * When advapi32.dll is unavailable or advapi32.dll has no SystemFunction036,
+   * also known as RtlGenRandom, which is the case for Windows versions prior
+   * to WinXP then c-ares uses portable rand() function. Then don't error here.
+   */
+
   hnd_advapi32 = 0;
   hnd_advapi32 = LoadLibrary("advapi32.dll");
-  if (!hnd_advapi32)
+  if (hnd_advapi32)
     {
-      FreeLibrary(hnd_iphlpapi);
-      return ARES_ELOADADVAPI32;
+      fpSystemFunction036 = (fpSystemFunction036_t)
+        GetProcAddress(hnd_advapi32, "SystemFunction036");
     }
 
-  fpSystemFunction036 = (fpSystemFunction036_t)
-    GetProcAddress(hnd_advapi32, "SystemFunction036");
-
-  /*
-   * Intentionally avoid checking if the address of SystemFunction036, a.k.a.
-   * RtlGenRandom, has been located or not. This function is only available on
-   * WinXP and later. When unavailable c-ares uses portable rand() function.
-   */
-
 #endif
   return ARES_SUCCESS;
 }

ares/ares_strerror.c

@@ -45,7 +45,6 @@ const char *ares_strerror(int code)
     "Given hostname is not numeric",
     "Illegal hints flags specified",
     "Error loading iphlpapi.dll",
-    "Error loading advapi32.dll",
     "Could not find GetNetworkParams function"
   };