libgdb.a contains debug_file_directory symbol (a static variable that goes to BSS section), but does not export it. Free Pascal Compiler has a Pascal unit (gdbint.ppu), that links against libgdb.a and initializes this variable. Unfortunately, since debug_file_directory is not exported, linking this unit fails. Please export the symbol.
The debug_file_directory symbol is exported since gdb-6.7
gdb-7.0.1-alt1 -> sisyphus: * Sun Mar 07 2010 Dmitry V. Levin <ldv@altlinux> 7.0.1-alt1 - Updated to 7.0.1 (closes: #19417, #20569, #21761). - Imported bunch of patches from FC gdb-7.0.1-33. - Imported bunch of patches from Debian gdb-7.0.1-2.