Auto merge of #29546 - alexcrichton:new-libc, r=brson

This commit replaces the in-tree liblibc with the [external clone](https://github.com/rust-lang-nursery/libc) which has no evolved beyond the in-tree version in light of its [recent redesign](rust-lang/rfcs#1291).

The primary changes here are:

* `src/liblibc/lib.rs` was deleted
* `src/liblibc` is now a submodule pointing at the external repository
* `src/libstd/sys/unix/{c.rs,sync.rs}` were both deleted having all bindings folded into the external liblibc.
* Many ad-hoc `extern` blocks in the standard library were removed in favor of bindings now being in the external liblibc.
* Many functions/types were added to `src/libstd/sys/windows/c.rs`, and the scattered definitions throughout the standard library were consolidated here.

At the API level this commit is **not a breaking change**, although it is only very lightly tested on the *BSD variants and is probably going to break almost all of their builds! Follow-up commits to liblibc should in theory be all that's necessary to get the build working on the *BSDs again.

.gitmodules

@@ -14,3 +14,6 @@
 [submodule "src/rust-installer"]
 	path = src/rust-installer
 	url = https://github.com/rust-lang/rust-installer
+[submodule "src/liblibc"]
+	path = src/liblibc
+	url = https://github.com/rust-lang/libc

mk/crates.mk

@@ -174,3 +174,6 @@ $(foreach crate,$(TOOLS),$(eval $(call RUST_TOOL,$(crate))))
 ifdef CFG_DISABLE_ELF_TLS
 RUSTFLAGS_std := --cfg no_elf_tls
 endif
+
+CRATEFILE_libc := $(SREL)src/liblibc/src/lib.rs
+RUSTFLAGS_libc := --cfg stdbuild

mk/tests.mk

@@ -22,7 +22,7 @@ $(eval $(call RUST_CRATE,coretest))
 DEPS_collectionstest :=
 $(eval $(call RUST_CRATE,collectionstest))
 
-TEST_TARGET_CRATES = $(filter-out core rustc_unicode alloc_system \
+TEST_TARGET_CRATES = $(filter-out core rustc_unicode alloc_system libc \
 		     		  alloc_jemalloc,$(TARGET_CRATES)) \
 			collectionstest coretest
 TEST_DOC_CRATES = $(DOC_CRATES)
@@ -283,6 +283,7 @@ tidy-binaries:
 		| grep '^$(S)src/compiler-rt' -v \
 		| grep '^$(S)src/libbacktrace' -v \
 		| grep '^$(S)src/rust-installer' -v \
+		| grep '^$(S)src/liblibc' -v \
 		| xargs $(CFG_PYTHON) $(S)src/etc/check-binaries.py
 
 .PHONY: tidy-errors

src/etc/tidy.py

@@ -108,7 +108,8 @@ def interesting_file(f):
             'src/rustllvm',
             'src/rt/valgrind',
             'src/rt/msvc',
-            'src/rust-installer'
+            'src/rust-installer',
+            'src/liblibc',
         }
 
         if any(d in dirpath for d in skippable_dirs):

src/liballoc_jemalloc/lib.rs

@@ -14,6 +14,7 @@
 #![staged_api]
 #![no_std]
 #![cfg_attr(not(stage0), allocator)]
+#![cfg_attr(stage0, allow(improper_ctypes))]
 #![unstable(feature = "alloc_jemalloc",
             reason = "this library is unlikely to be stabilized in its current \
                       form or name",

src/liballoc_system/lib.rs

@@ -14,6 +14,7 @@
 #![staged_api]
 #![no_std]
 #![cfg_attr(not(stage0), allocator)]
+#![cfg_attr(stage0, allow(improper_ctypes))]
 #![unstable(feature = "alloc_system",
             reason = "this library is unlikely to be stabilized in its current \
                       form or name",
@@ -141,10 +142,16 @@ mod imp {
 }
 
 #[cfg(windows)]
+#[allow(bad_style)]
 mod imp {
-    use libc::{BOOL, DWORD, HANDLE, LPVOID, SIZE_T};
     use MIN_ALIGN;
 
+    type LPVOID = *mut u8;
+    type HANDLE = LPVOID;
+    type SIZE_T = usize;
+    type DWORD = u32;
+    type BOOL = i32;
+
     extern "system" {
         fn GetProcessHeap() -> HANDLE;
         fn HeapAlloc(hHeap: HANDLE, dwFlags: DWORD, dwBytes: SIZE_T) -> LPVOID;

src/libflate/lib.rs

@@ -29,6 +29,7 @@
 #![feature(staged_api)]
 #![feature(unique)]
 #![cfg_attr(test, feature(rustc_private, rand, vec_push_all))]
+#![cfg_attr(stage0, allow(improper_ctypes))]
 
 #[cfg(test)]
 #[macro_use]