pinfo-0.6.13 build failure due to "-Werror"

[stefantalpalaru]

With gcc-8.3.0:

x86_64-pc-linux-gnu-gcc -DHAVE_CONFIG_H -I. -I..    -D_GNU_SOURCE -D_DEFAULT_SOURCE -I/usr/include/ncursesw -D_XOPEN_SOURCE=600  -Wall -Wextra -Wshadow -Werror -DLOCALEDIR=\"/usr/share/locale\" -DCONFIGDIR=\"/etc/pinforc\" -O3 -march=native -mlwp -pipe -D_BSD_SOURCE -D_DEFAULT_SOURCE  -D_XOPEN_SOURCE=600 -c -o pinfo-utils.o `test -f 'utils.c' || echo './'`utils.c
utils.c: In function ‘getstring_with_completion’:
utils.c:372:62: error: unused parameter ‘completions’ [-Werror=unused-parameter]
 getstring_with_completion(char *prompt, const char * const * completions)
                                         ~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~

[jwilk]

This only happens when building without readline enabled.