libutils: allow multiple ATRACE_NAMEs in a scope.

// See <cutils/trace.h> for more ATRACE_* macros.

// ATRACE_NAME traces the beginning and end of the current scope.  To trace

// the correct start and end times this macro should be declared first in the

// scope body.

#define ATRACE_NAME(name) android::ScopedTrace ___tracer(ATRACE_TAG, name)

// ATRACE_NAME traces from its location until the end of its enclosing scope.

#define _PASTE(x, y) x ## y

#define PASTE(x, y) _PASTE(x,y)

#define ATRACE_NAME(name) android::ScopedTrace PASTE(___tracer, __LINE__) (ATRACE_TAG, name)

// ATRACE_CALL is an ATRACE_NAME that uses the current function name.

#define ATRACE_CALL() ATRACE_NAME(__FUNCTION__)