Tests: Fix for non-Bash /bin/sh (#345)

* tests: Fix Bashism in POSIX shell script testContext.sh

Symptom was:
> # /bin/dash ./tests/lcov/extract/testContext.sh
> ./tests/lcov/extract/testContext.sh: 3: [: die: unexpected operator
> [..]

Signed-off-by: Sebastian Pipping <[email protected]>

* tests: Add missing portable Bash shebang line to script mcdc.sh

Symptom was:
> ./mcdc.sh: 61: [[: not found
> ./mcdc.sh: 70: Syntax error: "(" unexpected (expecting "then")

---------

Signed-off-by: Sebastian Pipping <[email protected]>

Author: hartwork

tests/lcov/extract/testContext.sh

@@ -1,6 +1,6 @@
 #!/bin/sh
 
-if [ 'die' == "$1" ] ; then
+if [ 'die' = "$1" ] ; then
     echo "dieing"
     exit 1
 fi

tests/lcov/mcdc/mcdc.sh

@@ -1,3 +1,4 @@
+#! /usr/bin/env bash
 CLEAN_ONLY=0
 COVER=