[automerger skipped] DO NOT MERGE: [libc++] Move __clamp_to_integral to <cmath>, and harden against min()/max() macros am: 7af7a63c2e am: d190f65c64 am: f0f107c222 -s ours am: b3d336063c -s ours am: c940a9b998 am: 30b59adf32 am: 9fe6d7544e
am: ad990058a3 -s ours
am skip reason: subject contains skip directive

Change-Id: Iea7f89b83aac8c6038b7ee44192ffe423cd83e83