tests: run tests for each arch

Since we can sign i386 PE/COFF images, run the tests on both x86-64 and
i386 binaries.

We do this by moving test.pecoff to test-<arch>.pecoff, and using
automake's parallel-test option to add a wrapper to each test execution.
This wrapper calls each test once per arch (as defined in TEST_ARCHES),
and checks for failures in any invocation.

Signed-off-by: Jeremy Kerr <jeremy.kerr@canonical.com>

tests/cert-table-header.sh

@@ -1,7 +1,5 @@
 #!/bin/bash -e
 
-. "$srcdir/common.sh"
-
 # Parse the data directory of a PE/COFF file and returns two hex values:
 # the file offset and size of the signature table.
 function sigtable_params() {