Make SOABI match EXT_SUFFIX

Fixes msys2-contrib#119

Author: naveen521kk

configure.ac

@@ -5264,7 +5264,11 @@ AC_SUBST(SOABI)
 AC_MSG_CHECKING(ABIFLAGS)
 AC_MSG_RESULT($ABIFLAGS)
 AC_MSG_CHECKING(SOABI)
-SOABI='cpython-'`echo $VERSION | tr -d .`${ABIFLAGS}${PLATFORM_TRIPLET:+-$PLATFORM_TRIPLET}
+if test -n "${PYD_PLATFORM_TAG}"; then
+  SOABI=".cp${VERSION_NO_DOTS}-${PYD_PLATFORM_TAG}${SHLIB_SUFFIX}"
+else
+  SOABI='cpython-'`echo $VERSION | tr -d .`${ABIFLAGS}${PLATFORM_TRIPLET:+-$PLATFORM_TRIPLET}
+fi
 AC_MSG_RESULT($SOABI)
 
 # Release and debug (Py_DEBUG) ABI are compatible, but not Py_TRACE_REFS ABI