osi: Always implement strlcpy as osi_strlcpy

This function is inconsistently implemented by libc implementations
as it is not a standard ISO-C method. Rename the filler implementation
and make sure it is always used in place of the BSD version.

Bug: 379338269
Test: m com.android.btservices
Flag: EXEMPT, no logical change
Change-Id: I3c78d6e8ebf55da8137fbcced5aa9e97dbcf0b44