ntp: Reproducible build: Use fixed path to posix shell

At configure time, the ntp build goes looking on the build machine for a posix
shell, using `which` to find it. Under OE, it settles on hosttools/bash,
resulting in this build host path being written into several binaries.
This did not affect the Debian reproducibility project, presumably because it
consistently found bash at /bin/bash.

Don't go looking, just use a fixed path to /bin/sh instead.

Upstream-Status: Submitted http://bugs.ntp.org/show_bug.cgi?id=3551
Signed-off-by: Douglas Royds <douglas.royds@taitradio.com>
Signed-off-by: Khem Raj <raj.khem@gmail.com>
Signed-off-by: Armin Kuster <akuster808@gmail.com>

meta-networking/recipes-support/ntp/ntp/reproducibility-fixed-path-to-posix-shell.patch

@@ -0,0 +1,15 @@
+--- ntp-4.2.8p12.original/sntp/libopts/m4/libopts.m4	2018-11-12 17:54:57.747220846 +1300
++++ ntp-4.2.8p12/sntp/libopts/m4/libopts.m4	2018-11-12 18:00:50.626211641 +1300
+@@ -114,12 +114,6 @@
+   AC_PROG_SED
+   [while :
+   do
+-      POSIX_SHELL=`which bash`
+-      test -x "$POSIX_SHELL" && break
+-      POSIX_SHELL=`which dash`
+-      test -x "$POSIX_SHELL" && break
+-      POSIX_SHELL=/usr/xpg4/bin/sh
+-      test -x "$POSIX_SHELL" && break
+       POSIX_SHELL=`/bin/sh -c '
+           exec 2>/dev/null
+           if ! true ; then exit 1 ; fi

meta-networking/recipes-support/ntp/ntp_4.2.8p12.bb

@@ -12,6 +12,7 @@ DEPENDS = "libevent"
 
 SRC_URI = "http://www.eecis.udel.edu/~ntp/ntp_spool/ntp4/ntp-4.2/ntp-${PV}.tar.gz \
            file://ntp-4.2.4_p6-nano.patch \
+           file://reproducibility-fixed-path-to-posix-shell.patch \
            file://reproducibility-respect-source-date-epoch.patch \
            file://ntpd \
            file://ntp.conf \