android: De-inline sig*set functions

These functions are forced inline in bionic, so they are not available;
forward them instead.
android: Use atof rather than strtold

The bionic library does not implement strtold.
REVISIT: android: Disable backtraces

The stdout and stderr are not available on Android.
android: Support bionic's pthread
android: Support bionic's mmap

There is not an mmap64 available on Android.
android: Don't flush stdout

On android, stdout is dumped to /dev/null anyways.
android: Implement sort for bionic

The qsort_r function is not available in bionic, so use the 'else'
branch's implementation.
DOUBLECHECK: Make phobos' configure depend on libiberty's build

The parallel build used in Android routinely failed without this.
REMOVE?: Regenerate configure