configure: properly check for Windows SDK 8.1A

Due to the wildcard checking for it will actually attempt to check for the
SDK 8.0, which fails with Visual Studio 2013 because its SDK 8.0 apparently
lacks a midl.exe, so configure fails.

Change-Id: Ib0e61a3a999d6a2ebe16645225fc9838dab3bdb1

configure.ac

@@ -5096,7 +5096,7 @@ find_winsdk_version()
             return
         fi
         ;;
-    8.1)
+    8.1|8.1A)
         reg_get_value_32 "HKEY_LOCAL_MACHINE/SOFTWARE/Microsoft/Windows Kits/Installed Roots/KitsRoot81"
         if test -n "$regvalue"; then
             winsdktest=$regvalue
@@ -5104,7 +5104,7 @@ find_winsdk_version()
             return
         fi
         ;;
-    8.*)
+    8.0|8.0A)
         reg_get_value_32 "HKEY_LOCAL_MACHINE/SOFTWARE/Microsoft/Windows Kits/Installed Roots/KitsRoot"
         if test -n "$regvalue"; then
             winsdktest=$regvalue