For linux, enable softIoc to find .dbd relative to the executable
location.
The same could be done for other targets
*bsd
may have symlink /proc/curproc/file
fallback to sysctl() with KERN_PROC_PATHNAME
solaris
getexecname()
mac
_NSGetExecutablePath()
WIN32
GetModuleFileName(NULL)
others
out of luck...
