Add -fpermissive to linux standard c++ option define in linux.cf

Remove from individual Imakefiles.

Also, remove '#if 0' block in linux.cf, and remove empty
LinuxMachineDefines. This should be working correctly.  If not, let me
know.

cde/programs/dtsearchpath/libCliSrv/Imakefile

@@ -22,10 +22,6 @@ EXTRA_DEFINES = -DIOSTREAMSWORKS
 EXTRA_DEFINES = -DIOSTREAMSWORKS
 #endif
 
-#if defined(LinuxArchitecture)
-CXXEXTRA_DEFINES = -fpermissive
-#endif
-
 SRCS =	DirIterator.C 	Environ.C 	TTFile.C \
 	UnixEnv.C	cstring.C