Fix coverage build on os-x

Squashed commit of the following:

commit 72ab42b890
Author: Joseph Birr-Pixton <jpixton@gmail.com>
Date:   Fri Sep 23 22:07:21 2016 +0100

    fix osx and leaving dangerous verify.rs around

commit f49bc6429f
Author: Joseph Birr-Pixton <jpixton@gmail.com>
Date:   Fri Sep 23 21:18:20 2016 +0100

    fix bogo instantiation

commit 047855a3c7
Author: Joseph Birr-Pixton <jpixton@gmail.com>
Date:   Fri Sep 23 21:09:56 2016 +0100

    don't use realpath, use readlink

commit e4a3e9bc50
Author: Joseph Birr-Pixton <jpixton@gmail.com>
Date:   Fri Sep 23 20:56:23 2016 +0100

    need coreutils

.travis.yml

@@ -14,5 +14,5 @@ script:
   - RUST_BACKTRACE=1 cargo test
   - cargo test --release --no-run
   - ./target/release/examples/bench
-  - cd bogo && ./runme
+  - ( cd bogo && ./runme )
   - if [[ "$TRAVIS_OS_NAME" == "linux" ]]; then ./admin/coverage   ; fi

admin/covbin/wrapper

@@ -1,6 +1,6 @@
-#!/bin/sh
+#!/bin/bash
 
-ME=$(realpath -s $0)
-WHICH=$(basename "$ME")
+ME=$([[ $0 = /* ]] && echo "$0" || echo "$PWD/${0#./}")
+WHICH=$(basename "$0")
 HERE=$(dirname "$ME")
 exec $COVERAGE $HERE/../../target/${RELEASE:-debug}/examples/$WHICH "$@"

admin/coverage

@@ -1,6 +1,6 @@
 #!/bin/sh
 
-export COVERAGE_OUT=$(realpath target)/coverage
+export COVERAGE_OUT=$PWD/target/coverage
 export KCOV_OPTIONS="kcov --exclude-pattern=/.cargo/,intrin.h --verify"
 export COVERAGE="$KCOV_OPTIONS $COVERAGE_OUT"
 export RUST_TEST_THREADS=1

bogo/runme

@@ -5,6 +5,7 @@
 
 set -xe
 
+cp ../src/verify.rs ../src/verify-secure.rs
 sed -i -e 's/\(DANGEROUS_DISABLE_VERIFY: bool = \)false/\1true/g' ../src/verify.rs
 cargo test --no-run
 
@@ -12,7 +13,8 @@ if [ ! -e bogo/ ] ; then
   ./fetch-and-build
 fi
 
-cd bogo && ./bogo.test -shim-path ../../admin/covbin/bogo_shim \
+( cd bogo && ./bogo.test -shim-path ../../admin/covbin/bogo_shim \
      -shim-config ../config.json \
      -test.parallel 1 -num-workers 1 \
-     -pipe -allow-unimplemented
+     -pipe -allow-unimplemented )
+mv ../src/verify-secure.rs ../src/verify.rs