test-lib: add "strip_path_prefix" to XSAN_OPTIONS

Change the stack traces emitted by the tests under LSAN and ASAN from
showing stack frames like:

    #0 0x4323b8 in malloc (/home/avar/g/git/t/helper/test-tool+0x4323b8)

To strip out the path to the build directory, so we'll instead emit:

    #0 0x4323b8 in malloc (t/helper/test-tool+0x4323b8)

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>

Author: avar

t/test-lib.sh

@@ -50,6 +50,7 @@ prepend_var () {
 
 # If [AL]SAN is in effect we want to abort so that we notice problems.
 prepend_var XSAN_OPTIONS : abort_on_error=1
+prepend_var XSAN_OPTIONS : strip_path_prefix=\"$GIT_BUILD_DIR/\"
 
 # If we were built with ASAN, it may complain about leaks
 # of program-lifetime variables. Disable it by default to lower