A `make check` failure due to missing cast in (unused?) test line.

[jefferys]

I'm getting the following error from make check.

...
make[2]: Entering directory '/tmpbuild/libgtextutils/tests'
...
g++ -DHAVE_CONFIG_H -I. -I..  -I../src   -g -O2 -Wall -Wextra -Wformat-nonliteral -Wformat-security -Wswitch-default -Wswitch-enum -Wunused-parameter -Wfloat-equal -Werror -DDEBUG -g -O1 -DDEBUG -g -O1 -MT test_in_out_buf.o -MD -MP -MF .deps/test_in_out_buf.Tpo -c -o test_in_out_buf.o test_in_out_buf.cpp
test_in_out_buf.cpp: In function 'int fork_pipe_command(const char*, const char*)':
test_in_out_buf.cpp:71:34: error: missing sentinel in function call [-Werror=format=]
  execlp(program,program,"-f",NULL);
                                  ^

I believe that line 71, from tests/test_in_out_buf.cpp, should be

  execlp(program,program,"-f",(char *)NULL);

But commenting it out allows all tests to run and pass, so it may not get used.

I'm building with docker from the current repo, I can replicate the error in isolation by creating an empty directory with just the (following) Dockerfile and from that directory running

docker build --tag fastx:edge .

This builds against the latest commit at the time of this issue, but uses its name so it should always be valid.

Dockerfile

FROM alpine:3.7

ARG LIBGTEXTUTILS_COMMIT=510270ecf2e342a81d5dffbf38505bfe18d23dca
RUN apk --no-cache add \
        autoconf \
        automake \
        bash \
        build-base \
        ca-certificates \
        curl \
        git  \
        libtool \
        make

RUN set -o pipefail \
    && mkdir -p /tmp/build \
    && cd /tmp/build  \
    && git clone https://github.com/agordon/libgtextutils.git \
    && cd libgtextutils \
    && git fsck \
    && git checkout $LIBGTEXTUTILS_COMMIT \
    && autoreconf -if \
    && aclocal \
    && autoconf \
    && automake \
    && ./configure \
    && make \
    && make check