Add FreeBSD to TravisCI

Implement the generation of Travis jobs for FreeBSD. The generated jobs
replicate the existing CirrusCI config.

scripts/freebsd/before_install.sh

@@ -0,0 +1,3 @@
+#!/bin/tcsh
+
+su -m root -c 'pkg install -y git'

scripts/freebsd/before_script.sh

@@ -0,0 +1,10 @@
+#!/bin/tcsh
+
+autoconf
+# We don't perfectly track freebsd stdlib.h definitions.  This is fine when
+# we count as a system header, but breaks otherwise, like during these
+# tests.
+./configure --with-jemalloc-prefix=ci_ ${COMPILER_FLAGS:+ CC="$CC $COMPILER_FLAGS" CXX="$CXX $COMPILER_FLAGS"} $CONFIGURE_FLAGS
+JE_NCPUS=`sysctl -n kern.smp.cpus`
+gmake -j${JE_NCPUS}
+gmake -j${JE_NCPUS} tests

scripts/freebsd/script.sh

@@ -0,0 +1,3 @@
+#!/bin/tcsh
+
+gmake check