fix argument omission in ABI-compat weak_alias for fscanf

Add ABI compatability aliases.

GNU used several extensions that were incompatible with C99 and POSIX,
so they used alternate names for the standard functions.

The result is that we need these to run standards-conformant programs
that were linked with glibc.

use restrict everywhere it's required by c99 and/or posix 2008

to deal with the fact that the public headers may be used with pre-c99
compilers, __restrict is used in place of restrict, and defined
appropriately for any supported compiler. we also avoid the form
[restrict] since older versions of gcc rejected it due to a bug in the
original c99 standard, and instead use the form *restrict.

initial check-in, version 0.5.0