ART: Compress LengthPrefixedArray on 32-bit targets.

Previously, the LengthPrefixedArray<ArtMethod> on 32-bit
targets contained a 64-bit length field followed by the
ArtMethod elements with size only a multiple of 4, not 8.
Consequently, an odd-length array broke the alignment for
the following array which would have the 64-bit length
placed at an unaligned address.

To fix that, we make the length field 32-bit and explicitly
pass the alignment information to the LengthPrefixedArray.
This also makes the 32-bit boot image a bit smaller.
On Nexus 5, AOSP, ToT, the field section is 11528B smaller
and the method section is 21036B smaller. 64-bit targets
should see the same savings for the field section but no
difference for the methods section.

Change-Id: I3e03e7b94129025c8a1c117c27645a34dec516d2
diff --git a/runtime/base/bit_utils.h b/runtime/base/bit_utils.h
index 6f45dc8..1da6750 100644
--- a/runtime/base/bit_utils.h
+++ b/runtime/base/bit_utils.h
@@ -158,6 +158,9 @@
 #define DCHECK_ALIGNED(value, alignment) \
   DCHECK(::art::IsAligned<alignment>(value)) << reinterpret_cast<const void*>(value)
 
+#define CHECK_ALIGNED_PARAM(value, alignment) \
+  CHECK(::art::IsAlignedParam(value, alignment)) << reinterpret_cast<const void*>(value)
+
 #define DCHECK_ALIGNED_PARAM(value, alignment) \
   DCHECK(::art::IsAlignedParam(value, alignment)) << reinterpret_cast<const void*>(value)