Don't use `git submodule update --init` in Makefile

This is because when we make tar ball, we are no longer under git
control.  git submodule does not work there.  We instead bundle mruby
source tree in archive.  git submodule command is only required when
building from git repository.

.travis.yml

@@ -31,6 +31,7 @@ before_script:
   - autoreconf -i
   - automake
   - autoconf
+  - git submodule update --init
   - ./configure --enable-werror --with-mruby
 script:
   - make

README.rst

@@ -139,8 +139,9 @@ To compile the source code, gcc >= 4.8.3 or clang >= 3.4 is required.
 
 .. note::
 
-   To enable mruby support in nghttpx, use ``--with-mruby`` configure
-   option.
+   To enable mruby support in nghttpx, run ``git submodule update
+   --init`` before running configure script, and use ``--with-mruby``
+   configure option.
 
 .. note::
 

makerelease.sh

@@ -6,6 +6,7 @@ PREV_TAG=$2
 git checkout refs/tags/$TAG
 git log --pretty=fuller --date=short refs/tags/$PREV_TAG..HEAD > ChangeLog
 
-./configure && \
+git submodule update --init
+./configure --with-mruby && \
     make dist-bzip2 && make dist-gzip && make dist-xz || echo "error"
 make distclean

third-party/Makefile.am

@@ -30,12 +30,13 @@ libhttp_parser_la_SOURCES = \
 	http-parser/http_parser.c \
 	http-parser/http_parser.h
 
-.PHONY: all-local clean mruby
-
 if HAVE_MRUBY
 
+EXTRA_DIST = build_config.rb mruby/*
+
+.PHONY: all-local clean mruby
+
 mruby:
-	git submodule update --init
 	MRUBY_CONFIG="${srcdir}/build_config.rb" \
 	BUILD_DIR="${abs_builddir}/mruby/build" \
 	CC="${CC}" CXX="${CXX}" LD="${LD}" \