add a dependency on makestrs to help with parallel builds

Signed-off-by: Thomas E. Dickey <dickey@invisible-island.net>

configure.ac

@@ -23,8 +23,7 @@
 
 # Initialize Autoconf
 AC_PREREQ([2.60])
-AC_INIT([libXt],
-    [1.2.0],
+AC_INIT([libXt], [1.2.0],
 	[https://gitlab.freedesktop.org/xorg/lib/libXt/issues], [libXt])
 AC_CONFIG_SRCDIR([Makefile.am])
 AC_CONFIG_HEADERS([config.h])

src/Makefile.am

@@ -96,10 +96,13 @@ all-local: $(BUILT_FILES)
 
 $(BUILT_HEADER): $(BUILT_SOURCE)
 
-$(BUILT_SOURCE):
+$(BUILT_SOURCE): $(top_builddir)/util/makestrs$(EXEEXT) 
 	$(AM_V_GEN)$(top_builddir)/util/makestrs -i $(top_srcdir) $(STRINGSABIOPTIONS) < $(STRING_LIST) > StringDefs.c
 	$(AM_V_at)$(MKDIR_P) $(top_builddir)/src
 	$(AM_V_at)$(MKDIR_P) $(top_builddir)/include/X11
 	$(AM_V_at)cp StringDefs.h $(top_builddir)/include/X11
 	$(AM_V_at)cp Shell.h $(top_builddir)/include/X11
 	$(AM_V_at)rm StringDefs.h Shell.h
+
+$(top_builddir)/util/makestrs$(EXEEXT) :
+	$(am__cd) $(@D) && $(MAKE) $(AM_MAKEFLAGS) $(@F)