Update build instructions

Author: ghorsington

README.md

@@ -15,10 +15,10 @@ gcc -shared -fPIC -o doorstop.so doorstop.c
 
 macOS:
 ```sh
-gcc -shared -fPIC -o doorstop.dylib doorstop.c
+gcc -shared -fPIC -o doorstop.dylib doorstop.c plthook_osx.c
 ```
 
-Or run `make` to generate both x86 and x64 builds.
+Or run either `make build_x64` or `make build_x86` depending on your architecture.
 
 ## How to use
 

makefile

@@ -1,16 +1,17 @@
 CC=gcc
 CCFLAGS=-shared -fPIC
-FILES=doorstop.c
 
 UNAME_S := $(shell uname -s)
 
 ifeq ($(UNAME_S), Linux)
 	EXT = so
 	CCFLAGS += -D LINUX
+	FILES=doorstop.c
 endif
 ifeq ($(UNAME_S), Darwin)
 	EXT = dylib
 	CCFLAGS += -D OSX
+	FILES=doorstop.c plthook_osx.c
 endif
 
 build: build_x86 build_x64