Don't ship .stp files when SystemTap support is disabled.

Related: rhbz#1657915

ruby.spec

@@ -701,12 +701,14 @@ sed -i '/^end$/ i\
 # Move man pages into proper location
 mv %{buildroot}%{gem_dir}/gems/rake-%{rake_version}/doc/rake.1 %{buildroot}%{_mandir}/man1
 
+%if %{with systemtap}
 # Install a tapset and fix up the path to the library.
 mkdir -p %{buildroot}%{tapset_dir}
 sed -e "s|@LIBRARY_PATH@|%{tapset_libdir}/libruby.so.%{major_minor_version}|" \
   %{SOURCE2} > %{buildroot}%{tapset_dir}/libruby.so.%{major_minor_version}.stp
 # Escape '*/' in comment.
 sed -i -r "s|( \*.*\*)\/(.*)|\1\\\/\2|" %{buildroot}%{tapset_dir}/libruby.so.%{major_minor_version}.stp
+%endif
 
 # Prepare -doc subpackage file lists.
 find doc -maxdepth 1 -type f ! -name '.*' ! -name '*.ja*' > .ruby-doc.en
@@ -945,7 +947,7 @@ OPENSSL_SYSTEM_CIPHERS_OVERRIDE=xyz_nonexistent_file OPENSSL_CONF='' \
 %{ruby_libarchdir}/syslog.so
 %{ruby_libarchdir}/zlib.so
 
-%{tapset_root}
+%{?with_systemtap:%{tapset_root}}
 
 %files -n rubygems
 %{_bindir}/gem
@@ -1015,7 +1017,7 @@ OPENSSL_SYSTEM_CIPHERS_OVERRIDE=xyz_nonexistent_file OPENSSL_CONF='' \
 %files doc -f .ruby-doc.en -f .ruby-doc.ja
 %doc README.md
 %doc ChangeLog
-%doc ruby-exercise.stp
+%{?with_systemtap:%doc ruby-exercise.stp}
 %{_datadir}/ri
 
 %files -n rubygem-bigdecimal
@@ -1099,6 +1101,8 @@ OPENSSL_SYSTEM_CIPHERS_OVERRIDE=xyz_nonexistent_file OPENSSL_CONF='' \
   * Remove Patch19: ruby-2.6.0-net-http-net-ftp-fix-session-resumption-with
       -TLS-1.3.patch; subsumed
   Resolves: rhbz#1688758
+- Don't ship .stp files when SystemTap support is disabled.
+  Related: rhbz#1657915
 
 * Fri Jan 11 2019 Jun Aruga <jaruga@redhat.com> - 2.5.3-103
 - Refresh expired certificates to fix FTBFS.