Make sure to install stubs/strutil.h
Generated code now pulls in this header transitively, so it needs to be
installed.
diff --git a/src/Makefile.am b/src/Makefile.am
index 76250d1..e5ba9b7 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -77,6 +77,7 @@
google/protobuf/stubs/status.h \
google/protobuf/stubs/stl_util.h \
google/protobuf/stubs/stringpiece.h \
+ google/protobuf/stubs/strutil.h \
google/protobuf/stubs/template_util.h \
google/protobuf/any.pb.h \
google/protobuf/api.pb.h \
@@ -195,7 +196,6 @@
google/protobuf/stubs/stringprintf.h \
google/protobuf/stubs/structurally_valid.cc \
google/protobuf/stubs/strutil.cc \
- google/protobuf/stubs/strutil.h \
google/protobuf/stubs/time.cc \
google/protobuf/stubs/time.h \
google/protobuf/arena.cc \