nghttpx: Don't add mruby related CPPFLAGS and LDFLAGS if it is disabled

Setting unused -L really makes libtool get angry

.travis.yml

@@ -31,7 +31,7 @@ before_script:
   - autoreconf -i
   - automake
   - autoconf
-  - ./configure --enable-werror
+  - ./configure --enable-werror --with-mruby
 script:
   - make
   - make check

src/Makefile.am

@@ -141,13 +141,16 @@ endif # HAVE_MRUBY
 
 noinst_LIBRARIES = libnghttpx.a
 libnghttpx_a_SOURCES = ${NGHTTPX_SRCS}
-libnghttpx_a_CPPFLAGS = ${AM_CPPFLAGS} \
-	-I${top_srcdir}/third-party/mruby/include @LIBMRUBY_CFLAGS@
+libnghttpx_a_CPPFLAGS = ${AM_CPPFLAGS}
 
 nghttpx_SOURCES = shrpx.cc shrpx.h
 nghttpx_CPPFLAGS = ${libnghttpx_a_CPPFLAGS}
-nghttpx_LDADD = libnghttpx.a ${LDADD} \
-	-L${top_builddir}/third-party/mruby/build/lib @LIBMRUBY_LIBS@
+nghttpx_LDADD = libnghttpx.a ${LDADD}
+
+if HAVE_MRUBY
+nghttpx_CPPFLAGS += -I${top_srcdir}/third-party/mruby/include @LIBMRUBY_CFLAGS@
+nghttpx_LDADD += -L${top_builddir}/third-party/mruby/build/lib @LIBMRUBY_LIBS@
+endif # HAVE_MRUBY
 
 if HAVE_CUNIT
 check_PROGRAMS += nghttpx-unittest
@@ -162,11 +165,15 @@ nghttpx_unittest_SOURCES = shrpx-unittest.cc \
 	buffer_test.cc buffer_test.h \
 	memchunk_test.cc memchunk_test.h
 nghttpx_unittest_CPPFLAGS = ${AM_CPPFLAGS} \
-	-I${top_srcdir}/third-party/mruby/include @LIBMRUBY_CFLAGS@ \
 	-DNGHTTP2_TESTS_DIR=\"$(top_srcdir)/tests\"
-nghttpx_unittest_LDADD = libnghttpx.a ${LDADD} \
-	-L${top_builddir}/third-party/mruby/build/lib @LIBMRUBY_LIBS@ \
-	@CUNIT_LIBS@ @TESTLDADD@
+nghttpx_unittest_LDADD = libnghttpx.a ${LDADD} @CUNIT_LIBS@ @TESTLDADD@
+
+if HAVE_MRUBY
+nghttpx_unittest_CPPFLAGS += \
+	-I${top_srcdir}/third-party/mruby/include @LIBMRUBY_CFLAGS@
+nghttpx_unittest_LDADD += \
+	-L${top_builddir}/third-party/mruby/build/lib @LIBMRUBY_LIBS@
+endif # HAVE_MRUBY
 
 TESTS += nghttpx-unittest
 endif # HAVE_CUNIT