Fix sh syntax issue in which2.sh

This fixes https://bugzilla.redhat.com/show_bug.cgi?id=1546221.
I also included three small spec cleanups:
* Removed Group tag.
* Removed buildroot cleaning in %install.
* Removed needless %defattr in %files.

which.spec

@@ -1,9 +1,8 @@
 Summary: Displays where a particular program in your path is located
 Name: which
 Version: 2.21
-Release: 7%{?dist}
+Release: 8%{?dist}
 License: GPLv3
-Group: Applications/System
 Source0: http://ftp.gnu.org/gnu/which/%{name}-%{version}.tar.gz
 Source1: which2.sh
 Source2: which2.csh
@@ -25,8 +24,6 @@ the specified program is in your PATH.
 make %{?_smp_mflags}
 
 %install
-rm -rf $RPM_BUILD_ROOT
-
 make install DESTDIR=$RPM_BUILD_ROOT
 
 mkdir -p $RPM_BUILD_ROOT%{_sysconfdir}/profile.d
@@ -44,7 +41,6 @@ fi
 exit 0
 
 %files
-%defattr(-,root,root)
 %license COPYING
 %doc EXAMPLES README AUTHORS NEWS
 %attr(0644,root,root) %{_sysconfdir}/profile.d/which2.*
@@ -53,6 +49,11 @@ exit 0
 %{_mandir}/*/*
 
 %changelog
+* Fri Feb 16 2018 Jason L Tibbitts III <tibbs@math.uh.edu> - 2.21-8
+- Fix invalid [ ... ] syntax which results in complaints by zsh.
+  https://bugzilla.redhat.com/show_bug.cgi?id=1546221
+- Remove pointless Group tag, buildroot cleaning and %%defattr.
+
 * Fri Feb 09 2018 Fedora Release Engineering <releng@fedoraproject.org> - 2.21-7
 - Rebuilt for https://fedoraproject.org/wiki/Fedora_28_Mass_Rebuild
 

which2.sh

@@ -1,6 +1,6 @@
 # Initialization script for bash and sh
 
-if [ "$0" == ksh ] ; then
+if [ "$0" = ksh ] ; then
   alias which='(alias; typeset -f) | /usr/bin/which --tty-only --read-alias --read-functions --show-tilde --show-dot'
 else
   alias which='(alias; declare -f) | /usr/bin/which --tty-only --read-alias --read-functions --show-tilde --show-dot'