bootstrap: Error out on failures

If we introduce any issues into our autotools scripts the ./bootstrap.sh
script doesn't error out. This allows our build scripts to continue on
potentially out of date copies of the Makefile.in and configure script
since the autoreconf didn't actually get to rewrite them successfully.

Tested:
    bootstrapping works as expected and introducing an error into
    configure.ac returns the correct error code.

Change-Id: I9f0976bbe88c89e7c436896703558c86cee19a9f
Signed-off-by: William A. Kennington III <wak@google.com>
diff --git a/bootstrap.sh b/bootstrap.sh
index 313001a..1be7493 100755
--- a/bootstrap.sh
+++ b/bootstrap.sh
@@ -1,4 +1,6 @@
 #!/bin/sh
+set -e
+set -x
 
 AUTOCONF_FILES="Makefile.in aclocal.m4 ar-lib autom4te.cache compile \
         config.guess config.h.in config.sub configure depcomp install-sh \