Fix Floss build breakage on ChromeOS

The bind.h header is now in base/functional/.

Bug: 309364342
Test: mmm packages/modules/Bluetooth
Test: USE="floss_upstream -cros-debug" emerge-brya floss
Flag: EXEMPT, fix build breakage
Change-Id: I8051241021f5cb165f4f496a126a84b4a8f21043