libgit2 @1.7.1: builds fail with xcode clang 6 and earlier: error: unknown type name 'inline'

[mascguy (Christopher Nielsen)]

Despite the project setting the C standard to 90 - which should (?) be sufficient - builds are failing due to keyword 'inline':

In file included from .../libgit2/work/libgit2-1.7.1/src/util/unix/posix.h:13:
/opt/local/include/LegacySupport/dirent.h:60:8: error: unknown type name 'inline'
static inline struct dirent *__mpls_readdir(DIR *dir) {
       ^

More frustratingly, libgit2-devel was updated to to this version three weeks ago, and it built successfully across-the-board. (Including 10.5, based on local testing.) So it's not clear what else has changed in that short time.