[BOLT] Ignore __hot_start, __hot_end from input

Summary:
When -hot-text is on, do not read __hot_start and __hot_end
from input (inserted by a linker script with the intent of ordering
functions). This can confuse BOLT into creating a function with this
name depending on which address the symbol lands and we will assert
when trying to emit our own __hot_start/__hot_end with symbol
redefinition.

(cherry picked from FBD24366636)