fix(lib,scheduler): allocation constructors and allocators report OOM instead of building NULL-name records (bug-1882)

make_alloc() and make_host_alloc() assigned strdup() results unchecked,
so under memory exhaustion they returned a record whose resname/reserve/
host was NULL; merge_job_alloc()'s same_alloc_slot() (bug-1863) then
strcmp()'d it (ASAN SEGV at xcealloc.c:337). make_alloc() also passed a
NULL resname straight to strdup().
- xcealloc.c: make_alloc()/make_host_alloc() reject a NULL name (EINVAL)
  and check every strdup(), freeing what they built and returning NULL
  (ENOMEM); on failure make_host_alloc()'s caller keeps `allocs`.
  dup_host_alloc() frees its partial copy on failure instead of leaking.
- scheduler.c sched_make_allocs(): a record that cannot be built fails
  the whole array (NULL, ENOMEM) instead of leaving a NULL entry.
- seqjob/parjob my_alloc(): check every constructor; on failure free
  what was built (parjob also rolls back the remaining claims) and
  return -ENOMEM with ctx->alloc NULL -- the caller moves ctx.alloc onto
  the job whatever the rc.

Tests: new xcealloc_oom_test (8, --wrap=strdup) and
sched_make_allocs_oom_test (real scheduler_srcs + --wrap=strdup); a new
-ENOMEM test in the seqjob and parjob allocator suites. All RED before
(SEGV / "Expected NULL" / "Expected -12 Was 1"), GREEN after.
xce-build.sh all asan: 115/115 suites OK, Go tests OK.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

src/lib/meson.build

@@ -241,3 +241,17 @@ libxce_test = executable('xcelib_test',
                          install: true)
 
 test('libxce test', libxce_test, timeout: 120)
+
+# bug-1882 regression: `-Wl,--wrap=strdup` linker symbol interposition (same
+# idiom as bug-1843's sched_record_lifecycle_test `--wrap=realloc`) so the
+# tests can make a chosen strdup() inside make_alloc()/make_host_alloc()
+# fail. Its own binary, so xcelib_test's other tests never see the wrap.
+libxce_alloc_oom_test = executable('xcealloc_oom_test',
+                                   ['testsuite/test_xcealloc_oom.c'],
+                                   include_directories: [incdir, build_inc],
+                                   dependencies: libxce_test_deps,
+                                   c_args: ['-DXCE_TESTING'],
+                                   link_args: ['-Wl,--wrap=strdup'],
+                                   install: false)
+
+test('libxce alloc OOM test', libxce_alloc_oom_test, timeout: 60)