Makefile.am: DISTCHECK_CONFIGURE_FLAGS -> AM_DISTCHECK_CONFIGURE_FLAGS

The Automake manual states: "The user can still extend or override
the flags provided there by defining the DISTCHECK_CONFIGURE_FLAGS
variable". Overriding variable DISTCHECK_CONFIGURE_FLAGS in Makefile.am
makes it impossible for the user to do that. I discovered this
when trying to pass --enable-internal-jimtcl to distcheck.

Change-Id: Ibe5b1f23ccf3fbaa21c48b574a1b3f3e9f6fb916
Signed-off-by: R. Diez <rdiezmail-openocd@yahoo.de>

Reviewed-on: https://review.openocd.org/c/openocd/+/8724
Reviewed-by: Antonio Borneo <borneo.antonio@gmail.com>
Tested-by: jenkins

Author: R. Diez

Makefile.am

@@ -7,7 +7,7 @@ AUTOMAKE_OPTIONS = gnu 1.6
 .DELETE_ON_ERROR:
 
 # make sure we pass the correct jimtcl flags to distcheck
-DISTCHECK_CONFIGURE_FLAGS = --disable-install-jim
+AM_DISTCHECK_CONFIGURE_FLAGS = --disable-install-jim
 
 # do not run Jim Tcl tests (esp. during distcheck)
 check-recursive: SUBDIRS :=