tcc.c: fix an error when you build an object file with '-pthread' key set
The problem was partially fixed by Henry in the following patch:
tcc.c: skip -lpthread when -c option specified
But that patch had one brawback: it is sensitive to argument order,
as decision is taken during commandline parsing:
$ tcc -c a.c -o a.o -pthread # 1. works fine
tcc: error: file 'a.c' not found
$ tcc -pthread -c a.c -o a.o # 2. blows
tcc: error: cannot specify libraries with -c
This patch fixes case 2.
Signed-off-by: Sergei Trofimovich <st@anti-virus.by>