prebuilt android tools: Init using SDK

Expose as an option for the cross stdenv.

lib/systems/default.nix

@@ -23,13 +23,15 @@ rec {
       config = parse.tripleFromSystem final.parsed;
       # Just a guess, based on `system`
       platform = platforms.selectBySystem final.system;
+      # Derived meta-data
       libc =
-        /**/ if final.isDarwin then "libSystem"
-        else if final.isMinGW  then "msvcrt"
-        else if final.isMusl  then "musl"
-        else if final.isLinux /* default */    then "glibc"
+        /**/ if final.isDarwin              then "libSystem"
+        else if final.isMinGW               then "msvcrt"
+        else if final.isMusl                then "musl"
+        else if final.isAndroid             then "bionic"
+        else if final.isLinux /* default */ then "glibc"
         # TODO(@Ericson2314) think more about other operating systems
-        else                        "native/impure";
+        else                                     "native/impure";
       extensions = {
         sharedLibrary =
           /**/ if final.isDarwin  then ".dylib"
@@ -39,7 +41,10 @@ rec {
           /**/ if final.isWindows then ".exe"
           else                         "";
       };
+      # Misc boolean options
+      useAndroidPrebuilt = false;
     } // mapAttrs (n: v: v final.parsed) inspect.predicates
       // args;
-  in final;
+  in assert final.useAndroidPrebuilt -> final.isAndroid;
+    final;
 }

lib/systems/examples.nix

@@ -38,6 +38,13 @@ rec {
     platform = platforms.aarch64-multiplatform;
   };
 
+  aarch64-android-prebuilt = rec {
+    config = "aarch64-unknown-linux-android";
+    arch = "aarch64";
+    platform = platforms.aarch64-multiplatform;
+    useAndroidPrebuilt = true;
+  };
+
   scaleway-c1 = armv7l-hf-multiplatform // rec {
     platform = platforms.scaleway-c1;
     inherit (platform.gcc) fpu;

lib/systems/inspect.nix

@@ -34,6 +34,7 @@ rec {
     Cygwin       = { kernel = kernels.windows; abi = abis.cygnus; };
     MinGW        = { kernel = kernels.windows; abi = abis.gnu; };
 
+    Android      = [ { abi = abis.android; } { abi = abis.androideabi; } ];
     Musl         = with abis; map (a: { abi = a; }) [ musl musleabi musleabihf ];
 
     Kexecable    = map (family: { kernel = kernels.linux; cpu.family = family; })

lib/systems/parse.nix

@@ -176,6 +176,7 @@ rec {
   types.abi = enum (attrValues abis);
 
   abis = setTypes types.openAbi {
+    android = {};
     cygnus = {};
     gnu = {};
     msvc = {};