support use of git submodules with the Makefiles

git=1 when invoking make will use the submodule submodules/lua.

On windows, it will also use the submodule submodules/pdcurses.

sys/unix/hints/linux.370

@@ -68,6 +68,17 @@ GAMEGRP  = games
 # you're reading this in Makefile augmented by hints, that may not be true).
 #
 
+ifeq "$(GIT)" "1"
+ifndef GITSUBMODULES
+GITSUBMODULES=1
+endif
+endif
+ifeq "$(git)" "1"
+ifndef GITSUBMODULES
+GITSUBMODULES=1
+endif
+endif
+
 #-INCLUDE multiw-2.370
 
 # compiler.370 contains compiler detection and adjustments common
@@ -237,10 +248,21 @@ POSTINSTALL+= sed -i -e 's;^GDBPATH=/usr/bin/gdb;\#GDBPATH=/usr/bin/gdb;' \
 		-e 's;PANICTRACE_GDB=1;PANICTRACE_GDB=0;' $(INSTDIR)/sysconf;
 endif
 
+# Lua
 # when building liblua.a, avoid warning that use of tmpnam() should be
 # replaced by mkstemp(); the lua code doesn't use nethack's config.h so
 # this needs to be passed via make rather than defined in unixconf.h
-SYSCFLAGS=-DLUA_USE_POSIX
+SYSCFLAGS=-DLUA_USE_LINUX
+ifdef GITSUBMODULES
+LUAFLAGS=CC='$(CC)' SYSCFLAGS='$(SYSCFLAGS)'
+ifneq "$(CCISCLANG)" ""
+# clang
+LUAFLAGS +=CWARNGCC=''
+endif   # clang
+override LUAHEADERS = submodules/lua
+override LUA2NHTOP = ../..
+override LUAMAKEFLAGS=$(LUAFLAGS)
+endif   # GITSUBMODULES
 
 # Only needed for GLIBC stack trace:
 LFLAGS=-rdynamic