Update build instructions.

README

@@ -6,12 +6,23 @@ License: GPLv2.  See COPYING for details.
 Dependencies:
 	libcurl			http://curl.haxx.se/libcurl/
 	jansson			http://www.digip.org/jansson/
-		(jansson is optional, and is included in-tree)
+	(jansson is included in-tree and an installed one may conflict)
 
 Basic *nix build instructions:
+	To build with GPU mining support:
+	Install AMD APP sdk, latest version - there is no offiical place to
+	install it so just keep track of where it is if you're not installing
+	the include files and library files into the system directory.
+	
 	./autogen.sh	# only needed if building from git repo
-	CFLAGS="-O3 -Wall -msse2" ./configure
+	CFLAGS="-O3 -Wall -march=native" ./configure
+	or if you haven't installed the ati files in system locations:
+	CFLAGS="-O3 -Wall -march=native -I<path to AMD APP include>" LDFLAGS="-L<path to AMD APP lib/x86_64> ./configure
 	make
+	
+	Note that you need to use /x86_64 for 64bit and /x86 for 32bit builds
+	If it finds the opencl files it will inform you with
+	"OpenCL: FOUND. GPU mining support enabled."
 
 Basic WIN32 build instructions (on Fedora 13; requires mingw32):
 	./autogen.sh	# only needed if building from git repo