enable parallel build

zsh.spec

@@ -3,7 +3,7 @@
 Summary: Powerful interactive shell
 Name: zsh
 Version: 5.3.1
-Release: 9%{?dist}
+Release: 10%{?dist}
 License: MIT
 URL: http://zsh.sourceforge.net/
 Group: System Environment/Shells
@@ -62,6 +62,9 @@ This package contains the Zsh manual in html format.
 %prep
 %autosetup -p1
 
+# enable parallel build
+sed -e 's|^\.NOTPARALLEL|#.NOTPARALLEL|' -i 'Config/defs.mk.in'
+
 %build
 # Compile with -fconserve-stack to prevent stack overflow while executing
 # unbounded call recursion in a shell script.  Without this compiler flag,
@@ -79,7 +82,10 @@ export LIBLDFLAGS='-z lazy'
     --enable-maildir-support \
     --enable-pcre
 
-make all html
+# prevent the build from failing while running in parallel
+make headers -C Src
+
+make %{?_smp_mflags} all html
 
 %check
 # Run the testsuite
@@ -173,6 +179,9 @@ fi
 %doc Doc/*.html
 
 %changelog
+* Fri Jul 07 2017 Kamil Dudka <kdudka@redhat.com> - 5.3.1-10
+- enable parallel build
+
 * Wed Jun 14 2017 Kamil Dudka <kdudka@redhat.com> - 5.3.1-9
 - fix unsafe use of a static buffer in history isearch (#1461483)