[musl] Remove LFS64 and _LARGEFILE64_SOURCE definitions

This was reverted previously as dart was using some of these
definitions. Dart has since been changed.

Test: full build, plus grep

Change-Id: Ibce5d9873b6132e5099370a5be7ddd54e7009aa2

[musl] Reintroduce LFS64 definitions

This partially reverts commit
e831a8265b4c3954eb78782c24ce5257520255b2.

These are currently used by the dart runtime. Once it is patched not
to do so, they will be removed again.

Test: built upper layers, including dart

Change-Id: I8261dd44c3ff0ceb067395afe76cb80f4c6f5a8e

[musl] Remove LFS64 definitions

Test: dash was the only client, and the shell still works

Change-Id: Ib5c2b99634b7b3545ef621096fe33663aadfb99f

[musl][bootloader] Use compiler-provided standard headers

<stdalign.h>, <stdarg.h>, <stdbool.h>, <stddef.h>, <stdint.h>
are all provided by the compiler and should not be replaced here.

The bootloader code's local versions were sloppy in what names
got defined where, so the code needed some #include additions
and type adjustments.

TC-32 #done

Change-Id: Ib24ba7b5072e99ec9302a6994d63ad5e16233151

[musl] Re-remove nonstandard major, minor, and makedev macros

These were temporarily reintroduced to facilitate the initial port of
sbase. Another CL teaches sbase about those bits, so that our
sys/types.h does not have to claim major and minor from the global
namespace.

Change-Id: I9025e68e12f311e82b6e70b2a2226c7cc6a57532

[musl] Re-introduce major, minor, and makedev macros

These were removed in I9ed6f259f32c6729ee3c05021d8b375e73f82e9c for
reasons that are no longer relevant.

These are harmless to have around under the _BSD_SOURCE guard, and
ease porting of POSIX-y software. For instance, sbase utilities have
these macros in some places into tar structs.

Change-Id: Id7ee85222f85cce2f89f96c8a2b56c4c610ed049

[musl] Remove nonstandard sysmacros.h

Change-Id: I9ed6f259f32c6729ee3c05021d8b375e73f82e9c

[musl] Use #pragma once in musl's public headers

Like the prior commit, this only replaces existing ifdef guards.

Change-Id: I39be129111db9f129aef72a53f986ce6a49376ac

[magenta] Initial commit