sim: generate build dependencies on the fly

Lift the code that GDB is using to generate dependencies on the fly and
port it over to the sim.  Now people shouldn't have to manually maintain
these in their Makefile's.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>

sim/common/acinclude.m4

@@ -21,6 +21,7 @@
 # Include global overrides and fixes for Autoconf.
 m4_include(../../config/override.m4)
 sinclude([../../config/zlib.m4])
+sinclude([../../config/depstand.m4])
 
 AC_DEFUN([SIM_AC_COMMON],
 [
@@ -45,6 +46,20 @@ AR=${AR-ar}
 AC_SUBST(AR)
 AC_PROG_RANLIB
 
+# Dependency checking.
+ZW_CREATE_DEPDIR
+ZW_PROG_COMPILER_DEPENDENCIES([CC])
+
+# Check for the 'make' the user wants to use.
+AC_CHECK_PROGS(MAKE, make)
+MAKE_IS_GNU=
+case "`$MAKE --version 2>&1 | sed 1q`" in
+  *GNU*)
+    MAKE_IS_GNU=yes
+    ;;
+esac
+AM_CONDITIONAL(GMAKE, test "$MAKE_IS_GNU" = yes)
+
 dnl We don't use gettext, but bfd does.  So we do the appropriate checks
 dnl to see if there are intl libraries we should link against.
 ALL_LINGUAS=