Commit 939da41143 added symbols redirections to handle ISO C
namespace, however some compiler does not support to redeclare the
function prototype. Moving these defintions to exported header
it not a good practice (it exposes a internal implementation and
it would require to add macros to define it only internally).
Instead this patch replaces the symbol redirections by direct asm
aliases, as done to handle libcall generation done by compiler on
some loop optimizations. The only issue is sparc binutils generates
an extra __mempcpy plt not called anywhere in the code, which indicates
a binutils issue (this is added in the localplt.data for now).
Checked on all affected ABIs.