chore: license text is actually NTP

While working on a DEP-5 machine readable copyright
file for the Debian packages, I noticed that the
SPDX tag differs from the actual license text.

The license text in question is identical to the
NTP license: https://spdx.org/licenses/NTP.html
(and not https://spdx.org/licenses/MIT.html).

Makefile.am

@@ -15,7 +15,7 @@
 # this software for any purpose.  It is provided "as is"
 # without express or implied warranty.
 #
-# SPDX-License-Identifier: MIT
+# SPDX-License-Identifier: NTP
 #
 #############################################################
 

Makefile.msvc

@@ -13,7 +13,7 @@
 # this software for any purpose.  It is provided "as is"
 # without express or implied warranty.
 #
-# SPDX-License-Identifier: MIT
+# SPDX-License-Identifier: NTP
 
 # ------------------------------------------------------------------------------
 #

test/Makefile.msvc

@@ -1,5 +1,5 @@
 # Copyright (C) The c-ares project and its contributors
-# SPDX-License-Identifier: MIT
+# SPDX-License-Identifier: NTP
 #
 # Permission to use, copy, modify, and distribute this
 # software and its documentation for any purpose and without