Add a warning to not edit env.mk

core/erlc.mk

@@ -259,6 +259,7 @@ define makedep.erl
 		end
 	end,
 	ok = file:write_file("$(1)", [
+		"# Generated by Erlang.mk. Edit at your own risk!\n\n",
 		[[F, "::", [[" ", D] || D <- Deps], "; @touch \$$@\n"] || {F, Deps} <- Depend],
 		"\nCOMPILE_FIRST +=", [[" ", TargetPath(CF)] || CF <- CompileFirst], "\n"
 	]),

plugins/c_src.mk

@@ -126,6 +126,7 @@ ifneq ($(wildcard $(C_SRC_DIR)),)
 $(C_SRC_ENV):
 	$(verbose) $(ERL) -eval "file:write_file(\"$(call core_native_path,$(C_SRC_ENV))\", \
 		io_lib:format( \
+			\"# Generated by Erlang.mk. Edit at your own risk!~n~n\" \
 			\"ERTS_INCLUDE_DIR ?= ~s/erts-~s/include/~n\" \
 			\"ERL_INTERFACE_INCLUDE_DIR ?= ~s~n\" \
 			\"ERL_INTERFACE_LIB_DIR ?= ~s~n\", \