Fix java-client generation of HIDL code

hidl_vec<T> and hidl_string was recently changed to use uint32_t for mSize
field instead of size_t. See ag/1640383
As a result Java clients started to crash because the size of hidl_vec and
hidl_string was reduced to 16 bytes and Java gen code was not adjusted.

Test: our java client is no longer crashing

Change-Id: I506ecd61277e3a4df96a10180c46ea924a42235d
Fix: b/33038659
diff --git a/StringType.cpp b/StringType.cpp
index d729efb..223d819 100644
--- a/StringType.cpp
+++ b/StringType.cpp
@@ -209,7 +209,7 @@
 
 void StringType::getAlignmentAndSize(size_t *align, size_t *size) const {
     *align = 8;  // hidl_string
-    *size = 24;
+    *size = 16;
 }
 
 }  // namespace android