eb596e885b0 breaks build: "'perf_data.pb.h' file not found"

Here's an excerpt from ninja's redirected stdout and stderr:

```
[3/238] Building CXX object CMakeFiles/create_gcov_lib.dir/sample_reader.cc.o
FAILED: CMakeFiles/create_gcov_lib.dir/sample_reader.cc.o
/usr/bin/clang++ -I../ -I../third_party/glog/src -I../third_party/abseil -I../third_party/perf_data_converter/src -I../third_party/perf_data_converter/src/quipper -I../util -I. -Ithird_party/glog -g -march=native -O3 -std=gnu++17 -MD -MT CMakeFiles/create_gcov_lib.dir/sample_reader.cc.o -MF CMakeFiles/create_gcov_lib.dir/sample_reader.cc.o.d -o CMakeFiles/create_gcov_lib.dir/sample_reader.cc.o -c ../sample_reader.cc
In file included from ../sample_reader.cc:6:
In file included from ../sample_reader.h:18:
In file included from ../third_party/perf_data_converter/src/quipper/perf_parser.h:18:
../third_party/perf_data_converter/src/quipper/base/macros.h:8:9: warning: 'DISALLOW_COPY_AND_ASSIGN' macro redefined [-Wmacro-redefined]
#define DISALLOW_COPY_AND_ASSIGN(TypeName) \
^
../base/macros.h:114:9: note: previous definition is here
#define DISALLOW_COPY_AND_ASSIGN(TypeName) \
^
In file included from ../sample_reader.cc:6:
In file included from ../sample_reader.h:18:
In file included from ../third_party/perf_data_converter/src/quipper/perf_parser.h:18:
../third_party/perf_data_converter/src/quipper/base/macros.h:12:9: warning: 'arraysize' macro redefined [-Wmacro-redefined]
#define arraysize(x) (sizeof(x) / sizeof(*x))
^
../base/macros.h:162:9: note: previous definition is here
#define arraysize(array) (sizeof(ArraySizeHelper(array)))
^
In file included from ../sample_reader.cc:6:
In file included from ../sample_reader.h:18:
In file included from ../third_party/perf_data_converter/src/quipper/perf_parser.h:21:
../third_party/perf_data_converter/src/quipper/compat/proto.h:14:10: fatal error: 'perf_data.pb.h' file not found
#include "perf_data.pb.h"
^~~~~~~~~~~~~~~~
2 warnings and 1 error generated.
```