FreeBSD apr1 upgrade error: Configure: 9904: Syntax error: word unexpected (expecting ")")

I was having trouble with apr1 on a FreeBSD web server. apr1 is used by Apache. The configure script for apr1 was dying with this error:

Performing libtool configuration ... 
. / configure: line 9904: syntax error near unexpected token `lt_decl_varnames, ' 

... which boiled down to:

. / configure: line 9904: `lt_if_append_uniq (lt_decl_varnames, SHELL,,, '

Fortunately, this thread was eventually resolved by someone finding out that they had some libtoo115 files left over, even though it had been deinstalled. I manually removed the extraneous files with:

# pkg_delete libtool-1.5.24 
# rm -rf /usr/local/share/libtool15 
# rm -f /usr/local/bin/libtool15 /usr/local/bin/libtoolize15

I am now back up and running!

Thanks to Vladislav Staroselskiy for a very helpful post about the FreeBSD apr1 libtool15 problem.