Fix anonymous struct and union warnings

gui/BufferItem.h and android/sensor.h uses anymous structs and nested
anonymous unions, which are GNU extensions.  sensor.h uses them as part
of its API, so disable the warnings in libgui, the only module that
tries to use it with -Weverything.  BufferItem.h only uses the unioned
fields inside libgui, remove the union and do the 64-bit to 32-bit
slicing manually so libvulkan doesn't need the warnings disabled.

Bug: 31752268
Test: m -j
Change-Id: I92d59b1202f4d6e5419edaa6d27b6e1c50ac0042
diff --git a/libs/gui/BufferItem.cpp b/libs/gui/BufferItem.cpp
index 5e3924a..1357a4a 100644
--- a/libs/gui/BufferItem.cpp
+++ b/libs/gui/BufferItem.cpp
@@ -23,6 +23,21 @@
 
 namespace android {
 
+template<typename T>
+static inline constexpr uint32_t low32(const T n) {
+    return static_cast<uint32_t>(static_cast<uint64_t>(n));
+}
+
+template<typename T>
+static inline constexpr uint32_t high32(const T n) {
+    return static_cast<uint32_t>(static_cast<uint64_t>(n)>>32);
+}
+
+template<typename T>
+static inline constexpr T to64(const uint32_t lo, const uint32_t hi) {
+    return static_cast<T>(static_cast<uint64_t>(hi)<<32 | lo);
+}
+
 BufferItem::BufferItem() :
     mGraphicBuffer(NULL),
     mFence(NULL),
@@ -56,12 +71,12 @@
     addAligned(size, mCrop);
     addAligned(size, mTransform);
     addAligned(size, mScalingMode);
-    addAligned(size, mTimestampLo);
-    addAligned(size, mTimestampHi);
+    addAligned(size, low32(mTimestamp));
+    addAligned(size, high32(mTimestamp));
     addAligned(size, mIsAutoTimestamp);
     addAligned(size, mDataSpace);
-    addAligned(size, mFrameNumberLo);
-    addAligned(size, mFrameNumberHi);
+    addAligned(size, low32(mFrameNumber));
+    addAligned(size, high32(mFrameNumber));
     addAligned(size, mSlot);
     addAligned(size, mIsDroppable);
     addAligned(size, mAcquireCalled);
@@ -141,12 +156,12 @@
     writeAligned(buffer, size, mCrop);
     writeAligned(buffer, size, mTransform);
     writeAligned(buffer, size, mScalingMode);
-    writeAligned(buffer, size, mTimestampLo);
-    writeAligned(buffer, size, mTimestampHi);
+    writeAligned(buffer, size, low32(mTimestamp));
+    writeAligned(buffer, size, high32(mTimestamp));
     writeAligned(buffer, size, mIsAutoTimestamp);
     writeAligned(buffer, size, mDataSpace);
-    writeAligned(buffer, size, mFrameNumberLo);
-    writeAligned(buffer, size, mFrameNumberHi);
+    writeAligned(buffer, size, low32(mFrameNumber));
+    writeAligned(buffer, size, high32(mFrameNumber));
     writeAligned(buffer, size, mSlot);
     writeAligned(buffer, size, mIsDroppable);
     writeAligned(buffer, size, mAcquireCalled);
@@ -194,15 +209,20 @@
         return NO_MEMORY;
     }
 
+    uint32_t timestampLo = 0, timestampHi = 0;
+    uint32_t frameNumberLo = 0, frameNumberHi = 0;
+
     readAligned(buffer, size, mCrop);
     readAligned(buffer, size, mTransform);
     readAligned(buffer, size, mScalingMode);
-    readAligned(buffer, size, mTimestampLo);
-    readAligned(buffer, size, mTimestampHi);
+    readAligned(buffer, size, timestampLo);
+    readAligned(buffer, size, timestampHi);
+    mTimestamp = to64<int64_t>(timestampLo, timestampHi);
     readAligned(buffer, size, mIsAutoTimestamp);
     readAligned(buffer, size, mDataSpace);
-    readAligned(buffer, size, mFrameNumberLo);
-    readAligned(buffer, size, mFrameNumberHi);
+    readAligned(buffer, size, frameNumberLo);
+    readAligned(buffer, size, frameNumberHi);
+    mFrameNumber = to64<uint64_t>(frameNumberLo, frameNumberHi);
     readAligned(buffer, size, mSlot);
     readAligned(buffer, size, mIsDroppable);
     readAligned(buffer, size, mAcquireCalled);