Remove frozen autoconf macros version a.k.a. "auto hacks"

This hasn't been maintained since 2007 and doesn't seem to be really
needed as using and not using them results in the same output currently.

build/autogen.mk

@@ -16,18 +16,11 @@
 ACLOCAL=aclocal
 AUTOCONF=autoconf
 BAKEFILE_GEN=bakefile_gen
-AUTOHACKS_PREPEND_INCLUDE_DIR=build/autoconf_prepend-include
 
 # configure depends on everything else so this will build everything.
 .PHONY: all
 all: configure
 
-.PHONY: autoconf_m4f
-
-# Invoke make on wxAutohacks dir, but don't fail if it's not present
-autoconf_m4f:
-	-make -C $(AUTOHACKS_PREPEND_INCLUDE_DIR)
-
 BAKEFILES=\
   build/bakefiles/wx.bkl \
   build/bakefiles/common.bkl \
@@ -46,9 +39,8 @@ autoconf_inc.m4 Makefile.in: $(BAKEFILES)
 	$(BAKEFILE_GEN) -f autoconf
 
 # Run configure whenever configure.in, aclocal.m4 or autoconf_inc.m4 is updated
-# Depend on our custom autoconf.m4f
-configure: configure.in aclocal.m4 autoconf_inc.m4 autoconf_m4f
-	$(AUTOCONF) -B $(AUTOHACKS_PREPEND_INCLUDE_DIR)
+configure: configure.in aclocal.m4 autoconf_inc.m4
+	$(AUTOCONF)
 
 ACLOCAL_SOURCES = \
   build/aclocal/ac_raf_func_which_getservbyname_r.m4 \