travis: Use nproc to speed up build (potentially)

.travis.yml

@@ -46,7 +46,7 @@ before_script:
   - autoreconf -i
   # Don't use ASAN for spdylay since failmalloc does not work with it.
   - ./configure --disable-src --disable-examples
-  - make check
+  - make -j$(nproc) check
   - export SPDYLAY_HOME=$PWD
   - cd ../..
   # Now build nghttp2
@@ -55,8 +55,8 @@ before_script:
   - if [ "$CI_BUILD" = "autotools" ]; then ./configure --enable-werror --with-mruby --with-neverbleed LIBSPDYLAY_CFLAGS="-I$SPDYLAY_HOME/lib/includes" LIBSPDYLAY_LIBS="-L$SPDYLAY_HOME/lib/.libs -lspdylay" CPPFLAGS=-fsanitize=address LDFLAGS=-fsanitize=address; fi
   - if [ "$CI_BUILD" = "cmake" ]; then cmake -DENABLE_WERROR=1 -DWITH_MRUBY=1 -DWITH_NEVERBLEED=1 -DSPDYLAY_INCLUDE_DIR="$SPDYLAY_HOME/lib/includes" -DSPDYLAY_LIBRARY="$SPDYLAY_HOME/lib/.libs/libspdylay.so"; fi
 script:
-  - if [ "$CI_BUILD" = "autotools" ]; then make distcheck; fi
-  - if [ "$CI_BUILD" = "cmake" ]; then make check; fi
+  - if [ "$CI_BUILD" = "autotools" ]; then make -j$(nproc) distcheck; fi
+  - if [ "$CI_BUILD" = "cmake" ]; then make -j$(nproc) check; fi
   # As of April, 23, 2016, golang http2 build fails, probably because
   # the default go version is too old.
   # - cd integration-tests