* Replace the save/load_buffer_state by a dynarray approach:
- Filename and libname are added to a dynarray when first encountered
- Load repeatedly the files in the dynarray until no new undefined
symbol are encountered
* Replace snprintf by sprintf in libname_to_filename
* Use tcc_fileextension in filename_to_libname
* Introduce a tcc_strcpy_part fonction to copy only a subset of a
string
* Move new_undef_syms declaration from tcc.h to tccelf.c
* search file from INPUT and GROUP commands in the library path in
addition to the current directory
* handle libraries specified by -lfoo options
* Search lib in GROUP command repeatedly
comparing the filenames as in the #include statement can be
ambiguous if including files are in different directories.
Now caches and checks the really opened filename instead.
