Mitigate stack frame size warning

With the latest AutoFDO data, the compiler emits the following warning:

ld.lld: error: art/runtime/gc/collector/mark_compact.cc:872:0: stack frame size (2224) exceeds limit (1744) in function '_ZN3art2gc9collector11MarkCompact9RunPhasesEv'

`ScopedPause pause` is the greatest contributor to the size (size:
1056). Move it to within MarkingPause to mitigate the warning.

Test: m libart
Flag: EXEMPT, bug fix
Change-Id: I258ea000536d669a5772f96e81a7241a030612ca
2 files changed