Make Mac SDK into a regular depends package

contrib/depends/README.md

@@ -30,7 +30,7 @@ Common `host-platform-triplets` for cross compilation are:
 
 - `i686-w64-mingw32` for Win32
 - `x86_64-w64-mingw32` for Win64
-- `x86_64-apple-darwin11` for MacOSX
+- `x86_64-apple-darwin11` for MacOSX x86_64
 - `arm-linux-gnueabihf` for Linux ARM 32 bit
 - `aarch64-linux-gnu` for Linux ARM 64 bit
 - `riscv64-linux-gnu` for Linux RISCV 64 bit
@@ -43,7 +43,6 @@ The following can be set when running make: make FOO=bar
 ```
 SOURCES_PATH: downloaded sources will be placed here
 BASE_CACHE: built packages will be placed here
-SDK_PATH: Path where sdk's can be found (used by OSX)
 FALLBACK_DOWNLOAD_PATH: If a source file can't be fetched, try here before giving up
 DEBUG: disable some optimizations and enable more runtime checking
 HOST_ID_SALT: Optional salt to use when generating host package ids
@@ -59,14 +58,6 @@ download-win: run 'make download-win' to fetch all sources needed for win builds
 download-linux: run 'make download-linux' to fetch all sources needed for linux builds
 ```
 
-#Darwin (macos) builds:
-
-To build with the x86_64-apple-darwin11 you require the mac os developer tools in MacOSX11.1.sdk.
-Download it from apple, or search for it on github. Create a new directoty called SDKs in this
-directory and place the entire MacOSX11.1.sdk folder in it. The depends build will then pick it up automatically
-(without requiring SDK_PATH). 
-
-
 #Mingw builds
 
 Building for 32/64bit mingw requires switching alternatives to a posix mode