NFC: Switch ATRACE_BUFFER_INDEX to be a more friendly macro statement.

In the process of upgrading to clang r349610, a new diagnostic,
-Wextra-semi-stmt, enabled by -Weverything catches redundant semicolons
in code.  ATRACE_BUFFER_INDEX is a macro statement (currently using an if
with a code block that ends in a '}'). Since most callers are treating
this as a pseudo-function call, they terminate the macro with a
semicolon. This triggers the diagnostic, as we now have "if (...) { ...
};", where the semicolon is unnecessary.

To remedy these kinds of situations, it is better to construct macro
statements that require a semicolon to terminate them. This patch uses a
do/while wrapped around the existing statement, which is a pretty common
pattern for macro statements.

Bug: http://b/122481018
Test: m checkbuild

Change-Id: Ib1271e8634b0a6bd05b27d78ae17f63feb0e5f65
diff --git a/libs/gui/include/gui/BufferQueueCore.h b/libs/gui/include/gui/BufferQueueCore.h
index 537c957..b377a41 100644
--- a/libs/gui/include/gui/BufferQueueCore.h
+++ b/libs/gui/include/gui/BufferQueueCore.h
@@ -40,13 +40,14 @@
 #define BQ_LOGW(x, ...) ALOGW("[%s] " x, mConsumerName.string(), ##__VA_ARGS__)
 #define BQ_LOGE(x, ...) ALOGE("[%s] " x, mConsumerName.string(), ##__VA_ARGS__)
 
-#define ATRACE_BUFFER_INDEX(index)                                   \
-    if (ATRACE_ENABLED()) {                                          \
-        char ___traceBuf[1024];                                      \
-        snprintf(___traceBuf, 1024, "%s: %d",                        \
-                mCore->mConsumerName.string(), (index));             \
-        android::ScopedTrace ___bufTracer(ATRACE_TAG, ___traceBuf);  \
-    }
+#define ATRACE_BUFFER_INDEX(index)                                                         \
+    do {                                                                                   \
+        if (ATRACE_ENABLED()) {                                                            \
+            char ___traceBuf[1024];                                                        \
+            snprintf(___traceBuf, 1024, "%s: %d", mCore->mConsumerName.string(), (index)); \
+            android::ScopedTrace ___bufTracer(ATRACE_TAG, ___traceBuf);                    \
+        }                                                                                  \
+    } while (false)
 
 namespace android {