fmtlib_ndk: set min_sdk_version to 29 am: 1a2a7fe335 am: 38f3565cb8 am: acc8cc825b

Original change: https://android-review.googlesource.com/c/platform/external/fmtlib/+/1477097

Change-Id: I57a5f1ff35daa41702c9eed5b254b0da563906b3