Build error

Nobody has claimed this yet.

I am using the `Dockerfile` and `README.md` info to try to build tippecanoe inside a container.

Here is what I have so fare:
```
FROM ubuntu:16.04

RUN apt-get update \
&& apt-get -y upgrade \
&& apt-get -y install build-essential libsqlite3-dev zlib1g-dev git

RUN git clone https://github.com/mapbox/tippecanoe.git
RUN cd tippecanoe
WORKDIR /tippecanoe

RUN make -j \
&& make install

RUN make test
```

Here is the output.
```
...

g++ -L/usr/local/lib -g -Wall -Wshadow -Wsign-compare -Wextra -Wunreachable-code -Wuninitialized -Wshadow -O3 -DNDEBUG -std=c++11 -o tippecanoe-enumerate enumerate.o -lsqlite3
mbtiles.cpp: In function 'void tilestats(const std::map, layermap_entry>&, size_t, json_writer&)':
mbtiles.cpp:133:7: warning: variable 'first' set but not used [-Wunused-but-set-variable]
bool first = true;
^
mbtiles.cpp: In function 'void mbtiles_write_metadata(sqlite3*, const char*, const char*, int, int, double, double, double, double, double, double, int, const char*, const std::map, layermap_entry>&, bool, const char*, bool, const std::map, std::__cxx11::basic_string >&, const string&, const string&)':
mbtiles.cpp:512:9: warning: variable 'first' set but not used [-Wunused-but-set-variable]
bool first = true;
^
Makefile:74: recipe for target 'decode.o' failed
g++: internal compiler error: Killed (program cc1plus)
Makefile:74: recipe for target 'main.o' failed
...
Please submit a full bug report,
with preprocessed source if appropriate.
See for instructions.
make: *** [main.o] Error 4
...
```

Any help on this appreciated.

### Update

Was able to build on Centos instead.
```
FROM centos:7

RUN mkdir /build
WORKDIR /build

RUN yum install -y make sqlite-devel zlib-devel bash git gcc-c++
WORKDIR /tippecanoe
RUN git clone https://github.com/mapbox/tippecanoe.git .
RUN make \
&& make install
```

Start with the Dockerfile and README.md instructions, then reproduce the Ubuntu 16.04 build using the shown make command and compiler output. Check whether the build completes and whether make test runs; the update reports a successful CentOS 7 build, so done would require a documented or reproducible resolution for the Ubuntu container.

Written by the indexing model from the issue text.