libgcrypt-config.in includes usage of fgrep, which is deprecated and prints a warning. see https://www.shellcheck.net/wiki/SC2196
for details.
this patch seems to be working fine:
--- libgcrypt-1.10.3.orig/src/libgcrypt-config.in +++ libgcrypt-1.10.3/src/libgcrypt-config.in @@ -154,7 +154,7 @@ if test "$echo_cflags" = "yes"; then tmp="" for i in $includes $cflags_final; do - if echo "$tmp" | fgrep -v -- "$i" >/dev/null; then + if echo "$tmp" | @GREP@ -F -v -- "$i" >/dev/null; then tmp="$tmp $i" fi done @@ -175,7 +175,7 @@ if test "$echo_libs" = "yes"; then tmp="" for i in $libdirs $libs_final; do - if echo "$tmp" | fgrep -v -- "$i" >/dev/null; then + if echo "$tmp" | @GREP@ -F -v -- "$i" >/dev/null; then tmp="$tmp $i" fi done