Enable linknamespace testing for libdl and libcrypt

[Joseph Myers]

On Wed, 16 Nov 2016, Florian Weimer wrote:

> On 11/16/2016 08:06 PM, Joseph Myers wrote:
> > +linknamespace-libs-XPG3 = $(linknamespace-libs-isoc) \
> > +			  $(common-objpfx)crypt/libcrypt.a
> 
> Does the linknamespace test perform a full link, and fails if it encounters
> undefined symbols?

No, it has its own emulation of linker logic, and ignores failure to find 
a definition of a symbol (for example, libgcc symbols - it doesn't look 
for libgcc.a / libgcc_eh.a, so it won't detect namespace issues there).  
(If an undefined symbol breaks namespace rules, that will still result in 
a test failure unless whitelisted in linknamespace.pl, whether or not a 
definition of that symbol was found.)

-- 
Joseph S. Myers
joseph@codesourcery.com