Configure fails with autoconf not found even though it's installed

Computing whether `autoconf` exists or not is done using the `which` command. The lack of `which` command on a system, even though `autoconf` exists, is signalled as being a problem with `autoconf` not being there, e.g.

11:54:03.576 [main] DEBUG FileSystem - Execute [bash, configure, --with-conf-name=graal-server-release, --disable-warnings-as-errors, --with-jvm-features=graal, --with-jvm-variants=server, --with-extra-cflags=-fcommon, --enable-aot=no, --with-boot-jdk=../../../boot-jdk-11] in /root/.qollider/cache/2306/jdk
Runnable configure script is not present
Generating runnable configure script at /root/.qollider/cache/2306/jdk/build/.configure-support/generated-configure.sh

Autoconf is not found on the PATH, and AUTOCONF is not set.
You need autoconf to be able to generate a runnable configure script.
Error: Cannot find autoconf

[root@7987ce27d191 /]# command -v which

[root@7987ce27d191 /]# command -v autoconf
/usr/bin/autoconf

A more reliable way, as suggested by Severin Gehwolf, would be to use `command -v` instead (as shown above).