Use static_cast to cast pointers returned by malloc/calloc/realloc/mmap.

static_cast is preferable to reinterpret_cast when casting from void*
pointers returned by malloc/calloc/realloc/mmap calls.

Discovered while looking at compiler warnings (b/26936282).

Test: WITH_TIDY=1 WITH_STATIC_ANALYZER=1 mma
Change-Id: Iaffd537784aa857108f6981fdfd82d0496eb5592
Merged-In: I151642d5a60c94f312d0611576ad0143c249ba3d