Fix ps name in Android subprocesses

Fix ps name in Android subprocesses

* exec/Makefile.in (.SUFFIXES): Include ., then `srcdir'.
* exec/loader-aarch64.s (_start):
* exec/loader-armeabi.s (_start):
* exec/loader-mips64el.s (__start):
* exec/loader-mipsel.s (__start):
* exec/loader-x86.s (_start):
* exec/loader-x86_64.s (_start): Get basename of opened exec
file and make it the command name.  Fix envp skipping on x86
and various leaks.