execs cannot be nested

build.xml

@@ -13,14 +13,15 @@
   <exec executable="tar" failonerror="true">
    <arg line="xf ${basedir}/packages/go/go1.12.6.src.tar.gz -C ${builddir}"/>
   </exec>
+  <exec executable="bash" outputproperty="CFLAGS">
+   <arg value="-c"/>
+   <arg value="if [ `uname -m` = 'x86_64' ] ; then echo -n '-mno-adx' ; fi"/>
+  </exec>
   <exec executable="./bootstrap.bash" dir="${makedir}/src">
    <env key="GOROOT_BOOTSTRAP" path="${builddir}/go1.4"/>
    <env key="GOOS" value="linux"/>
    <env key="GOARCH" value="${GOARCH}"/>
-   <exec executable="bash" outputproperty="CGO_CFLAGS">
-    <arg value="-c"/>
-    <arg value="if [ `uname -m` = 'x86_64' ] ; then echo -n '-mno-adx' ; fi"/>
-   </exec>
+   <env key="CGO_CFLAGS" value="${CFLAGS}"/>
   </exec>
   <exec executable="rm" failonerror="true">
    <arg line="-rf ${builddir}/go1.4"/>