TravisCI: use `if` block

.travis.yml

@@ -40,8 +40,8 @@ install:
   - if [ "$TRAVIS_OS_NAME" = "osx" -a "$BUNDLEDLIBTOM" != "--enable-bundled-libtom" ]; then brew update > /dev/null && brew install libtomcrypt libtommath ; fi
 
 script:
-  - autoconf && autoheader && ./configure $BUNDLEDLIBTOM CFLAGS="-O2 -Wall -Wno-pointer-sign $WEXTRAFLAGS" --prefix=$HOME/inst
-  - test "$NOWRITEV" && sed -i s/HAVE_WRITEV/DONT_HAVE_WRITEV/ config.h || true
+  - autoconf && autoheader && ./configure "$BUNDLEDLIBTOM" CFLAGS="-O2 -Wall -Wno-pointer-sign $WEXTRAFLAGS" --prefix="$HOME/inst"
+  - if [ "$NOWRITEV" = "1" ]; then sed -i s/HAVE_WRITEV/DONT_HAVE_WRITEV/ config.h ; fi
   - make -j3 install
 
 after_success: