google/protobuf/descriptor.proto: File not found

[byrnedo]

When building on ubuntu (following the steps in the readme)

Making all in src
make[1]: Entering directory '/home/donal/dev/service-proto/protoc-gen-php/src'
make  all-am
make[2]: Entering directory '/home/donal/dev/service-proto/protoc-gen-php/src'
protoc --proto_path=. --cpp_out=.  php_options.proto
google/protobuf/descriptor.proto: File not found.
php_options.proto: Import "google/protobuf/descriptor.proto" was not found or had errors.
php_options.proto:16:8: "google.protobuf.FileOptions" is not defined.
Makefile:636: recipe for target 'php_options.pb.cc' failed
make[2]: *** [php_options.pb.cc] Error 1
make[2]: Leaving directory '/home/donal/devservice-proto/protoc-gen-php/src'
Makefile:294: recipe for target 'all' failed
make[1]: *** [all] Error 2
make[1]: Leaving directory '/home/donal/dev/service-proto/protoc-gen-php/src'
Makefile:364: recipe for target 'all-recursive' failed
make: *** [all-recursive] Error 1