Fix ineffective DEAD clause for 32-bit configurations

Our packaging scripts set "!lal" for cross-Linux; these two testcases fall
through the crack for armhf-linux and ppc-linux because "!lal DEAD" is
superseded by "32bits OUT".

We could do a sweeping change to convert all "!x DEAD" tests to "x
REQUIRED"; in practice only these two are running for configs they should
not, so limit the churn.

- - -

FTR, this was caught after tweaking the test dependencies for cross
platforms.  In addition to a target-specific GNAT distribution, our
packaging scripts also pulled a full native GNAT distribution (including
gnatcoll-core, xmlada & aws); the tweak consisted in demoting that native
GNAT to just a native GCC compiler (excluding gnatcoll-core, xmlada & aws).

Before that tweak, these two tests were running successfully, because
ada2wsdl resolved the project file's 'with "aws"' using the native GNAT's
gnatcoll-core & xmlada.

After the tweak, ada2wsdl cannot find these libraries anymore.  Our
cross-platform GNAT distributions do include (a) native tools like ada2wsdl
(b) cross-platform gnatcoll-core & xmlada libraries, so it is actually
possible to have these tests pass: one hitch though is that our build
scripts install libraries in two places:
<compiler_prefix>/<CANONICAL_TARGET_NAME>/<runtime>/share/gpr
<compiler_prefix>/<TARGET_COMPILER_TRIPLET>/<runtime>/share/gpr

This forces us to set GPR_PROJECT_PATH to help ada2wsdl find the project
files to import, since we cannot pass --target=<TARGET_COMPILER_TRIPLET>
like we do for GPRbuild - who loads both, by virtue of heeding --target
_and_ also looking up the directory under <CANONICAL_TARGET_NAME>.

So the path to enabling ada2wsdl tests for cross platforms requires:

(a) converging on eng/gpr/gpr-issues#292 - consistently package libraries
    under <CANONICAL_TARGET_NAME> only,

(b) teaching these tests to pass a target to ada2wsdl, e.g. indirectly using
    an 'external' variable in their GPR file.

- - -

First things first though: get these spurious regressions off our QA radar.

TN: eng/toolchain/aws#49

regtests/0355_wsdl_decimal/test.opt

@@ -1,3 +1,3 @@
-!lal DEAD
-!xmlada DEAD
+lal REQUIRED
+xmlada REQUIRED
 32bits OUT test32b.out

regtests/0359_decimal_constraints/test.opt

@@ -1,3 +1,3 @@
-!lal DEAD
-!xmlada DEAD
+lal REQUIRED
+xmlada REQUIRED
 32bits OUT test32b.out