Fix program symbols exported in dynsym section
Fix program symbols exported in dynsym section

Prior to this commit TinyCC was exporting symbols defined in programs
only when they resolve an undefined symbol of a library. However, the
expected behavior (see --export-dynamic in GNU ld manpage) is that all
symbols used by libraries and defined by a program should be exported in
dynsym section. This is because symbol resolution search first in
program and then in libraries, thus allowing program symbol to interpose
symbol defined in a library.

seyko2/tinycc,seyko2/tinycc,mirror/tinycc,andrewchambers/tccmirror,mingodad/tinycc,mingodad/tinycc,mingodad/tinycc,metaeducation/tcc,run4flat/tinycc,avih/tinycc,fstudio/tinycc,andreiw/tinycc,avih/tinycc,fstudio/tinycc,andrewchambers/tccmirror,mirror/tinycc,metaeducation/tcc,code4game/tinycc,run4flat/tinycc,metaeducation/tcc,code4game/tinycc,run4flat/tinycc,andreiw/tinycc,fstudio/tinycc,seyko2/tinycc,andrewchambers/tccmirror,andreiw/tinycc,metaeducation/tcc,seyko2/tinycc,run4flat/tinycc,seyko2/tinycc,mirror/tinycc,metaeducation/tcc,andrewchambers/tccmirror,code4game/tinycc,fstudio/tinycc,avih/tinycc,mirror/tinycc,mingodad/tinycc,andrewchambers/tccmirror,fstudio/tinycc,run4flat/tinycc,avih/tinycc