hooks: redirect FILE* usage in all the stdio methods

 * All the methods of bionic's stdio that use a FILE* argument are now redirected, so that we can use the correct stdin,stdout or stderr if needed
 * fopen, fdopen, popen are hooked to the glibc version of the functions
 * __isthreaded symbol has been hooked to force the programs to use the thread-safe version of some stdio methods instead of an inline hard-coded implementation that uses the bionic FILE structure directly. See comments in hooks.c for details.

Signed-off-by: Christophe Chapuis <chris.chapuis@gmail.com>