autotools: fix make dist (#414)

Author: carenas

Makefile.am

@@ -277,7 +277,7 @@ EXTRA_DIST += \
 EXTRA_DIST += \
   vms/configure.com \
   vms/openvms_readme.txt \
-  vms/pcre2.h.patch \
+  vms/pcre2.h_patch \
   vms/stdint.h
 
 # These files are used in the preparation of a release