cmake lib lib64 problem

As discussed here, there's a semi-standardized way to inform
cmake that the install target wants its libs in .../lib64

https://code.google.com/p/bullet/issues/detail?id=174

this patch adds the necessary fiddling

Signed-off-by: Andy Green <andy.green@linaro.org>

CMakeLists.txt

@@ -679,7 +679,7 @@ if (UNIX)
 file(WRITE ${PROJECT_BINARY_DIR}/libwebsockets.pc
 "prefix=/usr/local
 exec_prefix=\${prefix}
-libdir=\${exec_prefix}/lib
+libdir=\${exec_prefix}/lib${LIB_SUFFIX}
 includedir=\${prefix}/include
 
 Name: libwebsockets
@@ -702,8 +702,8 @@ set(CPACK_COMPONENT_HEADERS_DISPLAY_NAME "Header files")
 
 # Install libs.
 install(TARGETS websockets websockets_shared
-		LIBRARY DESTINATION lib
-		ARCHIVE DESTINATION lib
+		LIBRARY DESTINATION lib${LIB_SUFFIX}
+		ARCHIVE DESTINATION lib${LIB_SUFFIX}
 		COMPONENT libraries)
 set(CPACK_COMPONENT_LIBRARIES_DISPLAY_NAME "Libraries")
 

README.build

@@ -283,12 +283,19 @@ Building on Unix:
 	 the source directory of libwebsockets containing the CMakeLists.txt project
 	 file. All examples in this file assumes you use "..")
 
+	NOTE2
 	A common option you may want to give is to set the install path, same
 	as --prefix= with autotools.  It defaults to /usr/local.
 	You can do this by, eg
 
 	cmake .. -DCMAKE_INSTALL_PREFIX:PATH=/usr
 
+	NOTE3
+	On machines that want libraries in lib64, you can also add the
+	following to the cmake line
+
+		-DLIB_SUFFIX=64
+
 4. Finally you can build using the generated Makefile:
 
 	make