[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

[bootloader] Report SMBIOS entry point to zircon

This adds a new bootdata type, BOOTDATA_SMBIOS, which provides the
address of the SMBIOS entry point table.

Change-Id: I59b6454b81146e822da6c6f084f6333880fab314

[kernel][pc] Finish C++ conversion

Change-Id: Iea6ff5e497597c1b0cd3a914e1a3cdd5b641cf58

[bootloader][magenta] move efi headers to shared location

Change-Id: I2851899efe8f0e1121170c08aa8d56c8112e7835