Merge pull request #41 from williamthome/fix/makefile

Fix Makefile issue

Author: mworrell

c_src/Makefile

@@ -6,9 +6,9 @@ BASEDIR := ..
 PROJECT ?= $(notdir $(BASEDIR))
 PROJECT := $(strip $(PROJECT))
 
-ERTS_INCLUDE_DIR ?= $(shell erl -noshell -eval "io:format(\"~s/erts-~s/include/\", [code:root_dir(), erlang:system_info(version)]), halt().")
-ERL_INTERFACE_INCLUDE_DIR ?= $(shell erl -noshell -eval "io:format(\"~s\", [code:lib_dir(erl_interface, include)]), halt().")
-ERL_INTERFACE_LIB_DIR ?= $(shell erl -noshell -eval "io:format(\"~s\", [code:lib_dir(erl_interface, lib)]), halt().")
+ERTS_INCLUDE_DIR ?= $(shell erl -noshell -eval 'io:format("~s/erts-~s/include/", [code:root_dir(), erlang:system_info(version)]).' -s erlang halt)
+ERL_INTERFACE_INCLUDE_DIR ?= $(shell erl -noshell -eval 'io:format("~s", [code:lib_dir(erl_interface, include)]).' -s erlang halt)
+ERL_INTERFACE_LIB_DIR ?= $(shell erl -noshell -eval 'io:format("~s", [code:lib_dir(erl_interface, lib)]).' -s erlang halt)
 
 C_SRC_DIR = $(CURDIR)
 C_SRC_NIF = $(CURDIR)/../priv/bcrypt_nif.so