PPC/s390: [ubsan] Change Address typedef to uintptr_t

Port 2459046c

Original Commit Message:

    The "Address" type is V8's general-purpose type for manipulating memory
    addresses. Per the C++ spec, pointer arithmetic and pointer comparisons
    are undefined behavior except within the same array; since we generally
    don't operate within a C++ array, our general-purpose type shouldn't be
    a pointer type.

R=jkummerow@chromium.org, joransiu@ca.ibm.com, michael_dawson@ca.ibm.com
BUG=
LOG=N

Change-Id: Ic30ef19019e5b39b01f90587011c6a1b06c4b7a1
Reviewed-on: https://chromium-review.googlesource.com/1012461Reviewed-by: Junliang Yan <jyan@ca.ibm.com>
Commit-Queue: Junliang Yan <jyan@ca.ibm.com>
Cr-Commit-Position: refs/heads/master@{#52607}

src/ppc/assembler-ppc-inl.h

@@ -238,7 +238,7 @@ void RelocInfo::WipeOut() {
     Assembler::set_target_address_at(pc_, constant_pool_, kNullAddress,
                                      SKIP_ICACHE_FLUSH);
   } else {
-    Assembler::set_target_address_at(pc_, constant_pool_, kNullAddress0);
+    Assembler::set_target_address_at(pc_, constant_pool_, kNullAddress);
   }
 }