Darwin: Fix a typo in Objective-C meta-data.

Darwin: Fix a typo in Objective-C meta-data.

We have a typo in the metadata for assigning NSStrings to a specific
section for the V1 (32b) ABI.  When that is fixed we should never see
the case where the section needs to be deduced from the properties of
the DECLs.

gcc/ChangeLog:

	* config/darwin.cc (darwin_objc1_section): Use the correct
	meta-data version for constant strings.
	(machopic_select_section): Assert if we fail to handle CFString
	sections as Obejctive-C meta-data or drectly.

Signed-off-by: Iain Sandoe <iain@sandoe.co.uk>