Integrate change #12626 from maintperl;

Integrate change #12626 from maintperl;
make DynaLoader threadsafe by moving all statics into
interpreter-local space

TODO: Netware, OS/2, WinCE

p4raw-link: @12626 on //depot/maint-5.6/perl: 512dcce54ea4db665708f91609bdd0a6126d1acd

p4raw-id: //depot/perl@12627
p4raw-integrated: from //depot/maint-5.6/perl@12625 'copy in'
	ext/DynaLoader/dl_beos.xs ext/DynaLoader/dl_dld.xs
	ext/DynaLoader/dl_dyld.xs ext/DynaLoader/dl_hpux.xs
	ext/DynaLoader/dl_next.xs ext/DynaLoader/dl_vmesa.xs
	ext/DynaLoader/dl_vms.xs (@5902..) ext/DynaLoader/dl_dllload.xs
	(@8789..) 'merge in' ext/DynaLoader/dl_mpeix.xs
	ext/DynaLoader/dlutils.c win32/dl_win32.xs (@5902..)
	ext/DynaLoader/dl_dlopen.xs (@8631..) ext/DynaLoader/dl_aix.xs
	(@9416..) ext/DynaLoader/dl_mac.xs (@12597..)