ada: Rework s-linux/osinte for arm/aarch64-android sigactions

Building an aarch64-android compiler with the current sources
initially intended for arm-android expectedly trips on problems.

This change is meant to address:
```
.../gcc/ada/rts % ../../gnat1 -quiet ... a-stbufi.adb -I.

s-osinte.ads:591:07: error: component "sa_flags" overlaps "sa_mask" at line 590
```

s-linux__android.ads makes hardcoded assumptions on the size
of sigset_t, based on observations performed in the course of the
arm port.

Then sysem headers show sa_flags placed VERY differently between
the 32 and the 64 bits variants.

See android-sysroot/usr/include/bits/signal_types.h
```
%if defined(__LP64__)

  int sa_flags; \
  union { \
    sighandler_t sa_handler; \
    void (*sa_sigaction)(int, struct siginfo*, void*); \
  }; \
  sigset_t sa_mask; \
  void (*sa_restorer)(void); \

%else

  union {
    sighandler_t sa_handler;
    void (*sa_sigaction)(int, struct siginfo*, void*);
  };
  sigset_t sa_mask;
  int sa_flags;
  void (*sa_restorer)(void);

```

gcc/ada/ChangeLog:

	* libgnarl/s-linux__android-arm.ads: New file, renaming of ...
	* libgnarl/s-linux__android.ads: ... this file.
	* libgnarl/s-linux__android-aarch64.ads: New file. Based on the
	-arm variant, with sa_ field positions adjusted.
	* Makefile.rtl (arm/aarch64-android pairs): Adjust accordingly.
	* libgnarl/s-osinte__android.ads: Rather than making assumptions
	on the actual type of the C sigset_t, use
	Os_Constants.SIZEOF_sigset_t to define an Ada sigset_t type of the
	proper size. Use C.int instead of unsigned_long for sa_flags.

0 files changed, 0 insertions, 0 deletions