separate std.Target and std.zig.CrossTarget

Zig now supports a more fine-grained sense of what is native and what is
not. Some examples:

This is now allowed:
-target native

Different OS but native CPU, default Windows C ABI:
-target native-windows
This could be useful for example when running in Wine.

Different CPU but native OS, native C ABI.
-target x86_64-native -mcpu=skylake

Different C ABI but otherwise native target:
-target native-native-musl
-target native-native-gnu

Lots of breaking changes to related std lib APIs.
Calls to getOs() will need to be changed to getOsTag().
Calls to getArch() will need to be changed to getCpuArch().

Usage of Target.Cross and Target.Native need to be updated to use
CrossTarget API.

`std.build.Builder.standardTargetOptions` is changed to accept its
parameters as a struct with default values. It now has the ability to
specify a whitelist of targets allowed, as well as the default target.
Rather than two different ways of collecting the target, it's now always
a string that is validated, and prints helpful diagnostics for invalid
targets. This feature should now be actually useful, and contributions
welcome to further improve the user experience.

`std.build.LibExeObjStep.setTheTarget` is removed.
`std.build.LibExeObjStep.setTarget` is updated to take a CrossTarget
parameter.

`std.build.LibExeObjStep.setTargetGLibC` is removed. glibc versions are
handled in the CrossTarget API and can be specified with the `-target`
triple.

`std.builtin.Version` gains a `format` method.

1 files changed, 4 insertions, 6 deletions

diff --git a/lib/std/testing.zig b/lib/std/testing.zig
index 348f651a88..398a71ff37 100644
--- a/lib/std/testing.zig
+++ b/lib/std/testing.zig
@@ -1,5 +1,3 @@
-const builtin = @import("builtin");
-const TypeId = builtin.TypeId;
 const std = @import("std.zig");
 
 pub const LeakCountAllocator = @import("testing/leak_count_allocator.zig").LeakCountAllocator;
@@ -65,16 +63,16 @@ pub fn expectEqual(expected: var, actual: @TypeOf(expected)) void {
 
         .Pointer => |pointer| {
             switch (pointer.size) {
-                builtin.TypeInfo.Pointer.Size.One,
-                builtin.TypeInfo.Pointer.Size.Many,
-                builtin.TypeInfo.Pointer.Size.C,
+                .One,
+                .Many,
+                .C,
                 => {
                     if (actual != expected) {
                         std.debug.panic("expected {*}, found {*}", .{ expected, actual });
                     }
                 },
 
-                builtin.TypeInfo.Pointer.Size.Slice => {
+                .Slice => {
                     if (actual.ptr != expected.ptr) {
                         std.debug.panic("expected slice ptr {}, found {}", .{ expected.ptr, actual.ptr });
                     }