Restrict creation of bootreceiver tracing instance to 64-bit systems.

The main users of this instance are KFENCE and MTE-aided KASAN, which are only supported on arm64.
Skip creation of this tracing instance on 32-bit systems to save ~6Mb memory on low-end devices.

Bug: 195089948
Bug: 194719088
Bug: 194156700
Test: manual on Pixel device
Merged-In: Icaf762715fed7a282b1ad738c10bcb45dc848f4d
Change-Id: I61694ce174fa745ef9fd50ca7464b5a9e1d1e011
1 file changed