Run the build host mksignal and mkstatval.

diff -Nrup a/Makefile.am b/Makefile.am
--- a/Makefile.am	2015-05-16 22:23:26.000000000 +0200
+++ b/Makefile.am	2026-10-22 17:22:43.059958263 +0200
@@ -36,14 +36,14 @@ BUILT_SOURCES = sigmsgs.c
 EXTRA_DIST = EXAMPLES addon.c addon.h history.1 parse.y rc.1 trip.rc
 
 sigmsgs.c sigmsgs.h: mksignal
-	./mksignal
+	./mksignal.build
 
 # Newer automake's buildtime dependency tracking can't seem to figure
 # this one out.
 status.o: statval.h
 
 statval.h: mkstatval
-	./mkstatval > statval.h
+	./mkstatval.build > statval.h
 
 DISTCLEANFILES = sigmsgs.c sigmsgs.h statval.h