This patch is a follow on from D62853 . Although many relocatable objects will have a single GNU_PROPERTY_X86_FEATURE_1_AND in the .note.gnu.property section it is permissible to have more than one, and there is a test in ld.bfd that uses it. The behavior that ld.bfd follows is to set the feature bit for a relocatable object if any of the GNU_PROPERTY_X86_FEATURE_1_AND have the feature bit set.
The specific test in ld.bfd is https://github.com/bminor/binutils-gdb/blob/master/ld/testsuite/ld-aarch64/property-bti-pac1.s there isn't an X86 equivalent test but the same behaviour can be observed with IBT and SHSTK. I've added a test case for that.
This could be considered a corner case, however it is not known whether tools will just add another GNU_PROPERTY_X86_FEATURE_1_AND rather than find an existing one and add to it.