fix segmentation fault of pbc_disassemble.exe on mingw
fix segmentation fault of pbc_disassemble.exe on mingw

(gdb) bt
#0  0x686d491d in PDB_free_file (interp=0x3f4050, file=0xbaadf00d)
    at src/debug.c:2745
#1  0x686d4a75 in PDB_disassemble (interp=0x3f4050, command_unused=0x0)
    at src/debug.c:2612
#2  0x686d87a2 in Parrot_disassemble (interp=0x3f4050, outfile=0x0, options=0)
    at src/embed.c:969
#3  0x00401385 in do_dis (interp=0x3f4050, outfile=0x0, options=0)
    at src/pbc_disassemble.c:161
#4  0x00401527 in main (argc=1, argv=0x3f402c) at src/pbc_disassemble.c:141


git-svn-id: 6e74a02f85675cec270f5d931b0f6998666294a3@46058 d31e2699-5ff4-0310-a27c-f18f2fbe73fe

gagern/parrot,tkob/parrot,tewk/parrot-select,FROGGS/parrot,FROGGS/parrot,gagern/parrot,youprofit/parrot,parrot/parrot,parrot/parrot,FROGGS/parrot,FROGGS/parrot,parrot/parrot,FROGGS/parrot,fernandobrito/parrot,parrot/parrot,gagern/parrot,youprofit/parrot,youprofit/parrot,tewk/parrot-select,FROGGS/parrot,tewk/parrot-select,youprofit/parrot,tkob/parrot,fernandobrito/parrot,youprofit/parrot,tkob/parrot,tkob/parrot,youprofit/parrot,gitster/parrot,tkob/parrot,tkob/parrot,gagern/parrot,fernandobrito/parrot,tkob/parrot,gagern/parrot,tewk/parrot-select,FROGGS/parrot,gitster/parrot,gitster/parrot,gitster/parrot,tewk/parrot-select,tkob/parrot,fernandobrito/parrot,youprofit/parrot,gitster/parrot,gitster/parrot,tewk/parrot-select,gagern/parrot,gitster/parrot,fernandobrito/parrot,youprofit/parrot,fernandobrito/parrot,parrot/parrot,FROGGS/parrot,fernandobrito/parrot,gagern/parrot,tewk/parrot-select