add no-writev build

.travis.yml

@@ -3,7 +3,9 @@ compiler:
   - gcc
 
 script: 
-  - autoconf && autoheader && ./configure $BUNDLEDLIBTOM CFLAGS="-O2 -Wall -Wno-pointer-sign" --prefix=$HOME/inst && make install
+  - autoconf && autoheader && ./configure $BUNDLEDLIBTOM CFLAGS="-O2 -Wall -Wno-pointer-sign" --prefix=$HOME/inst 
+  - [ "$NOWRITEV" == 1 ] && sed -i s/HAVE_WRITEV/DONT_HAVE_WRITEV/ config.h
+  - make install
   - ~/inst/bin/dropbearkey -t rsa -f testrsa
   - ~/inst/bin/dropbearkey -t dss -f testdss
   - ~/inst/bin/dropbearkey -t ecdsa -f testec256 -s 256
@@ -18,3 +20,4 @@ env:
   - BUNDLEDLIBTOM=--disable-bundled-libtom
   - BUNDLEDLIBTOM=--enable-bundled-libtom
   - MULTI=1
+  - NOWRITEV=1