Change sample native-codec's minSDK to android-21

android-L is renamed as android-21 in both coming SDK and NDK

Change-Id: I57b0dbe4d6e8add178dadfa6306bfc40aad27206
Remove macros putc*/getc* from API<21 stdio.h to use

Macros putc, getc and their unlock cousins use internal functions and
variables not necessarily available in future libc.so (*1).  Remove macros
and use functions aleady exists in libc.so instead.

(*1) https://android-review.googlesource.com/#/c/110662/

Change-Id: I3faa2d74de40ef8376119b38f2a39d46ece47d07
Add asm/a.out.h to arm64/mips/mips64

The common header include/linux/a.out.h include asm/a.out.h, but
arm64/mips/mips64 don't have it.  Add a placeholder before bionic
has it

Change-Id: I7084e0beabe86fec32987a89e66d6c094f1e8c22
Merge "Change sample native-codec's minSDK to android-21"
Merge "Remove macros putc*/getc* from API<21 stdio.h to use"
Merge "Add asm/a.out.h to arm64/mips/mips64"