fix(build): bare 'make test/<bin>' errors instead of linking a broken dylib

The per-binary test rules only exist in the Makefile's TEST_EXPORTS=1
branch.  A bare 'make test/test_cd_hle_boot' fell through to GNU make's
built-in %:%.c rule, which links with the core's -dynamiclib LDFLAGS
and produces an unexecutable shared library.  cd_boot_matrix.sh built
its harnesses exactly that way, so every row of a fresh matrix
regeneration came back '?' with "cannot execute binary file" in the
per-run logs.

Add a loud pattern-rule guard in the non-TEST_EXPORTS branch, and make
cd_boot_matrix.sh build with TEST_EXPORTS=1 and re-link when an
existing file isn't a real executable.

Co-Authored-By: Claude Fable 5 <[email protected]>

Makefile

@@ -760,6 +760,17 @@ else ifneq ($(TEST_EXPORTS),1)
 test:
 	@rm -f $(TARGET)
 	@$(MAKE) TEST_EXPORTS=1 test
+
+# The per-binary rules below only exist in the TEST_EXPORTS=1 branch.
+# Without this guard, a bare `make test/<binary>` silently falls through
+# to GNU make's built-in %:%.c rule, which links with the core's
+# -dynamiclib LDFLAGS and produces an UNEXECUTABLE shared library
+# ("cannot execute binary file" at run time -- this broke
+# cd_boot_matrix.sh's harness build).  Fail loudly instead.
+test/test_% test/tools/test_%:
+	@echo "ERROR: test binaries need the TEST_EXPORTS=1 rule set:" >&2
+	@echo "  make TEST_EXPORTS=1 $@" >&2
+	@false
 else
 # Every harness that dlopens the core verifies the binary's embedded git
 # rev (+ -dirty) against this before running -- a stale dylib fails loudly

test/tools/cd_boot_matrix.sh

@@ -119,10 +119,16 @@ if [ -n "$VJ_EXPECT_BUILD" ]; then
     fi
 fi
 
+# TEST_EXPORTS=1 is required: the per-binary rules only exist in that
+# Makefile branch.  A bare `make test/<bin>` falls through to GNU make's
+# built-in %:%.c rule, which links with the core's -dynamiclib LDFLAGS
+# and produces an unexecutable shared library (every matrix row then
+# reads "cannot execute binary file" -> all '?').
 for bin in test/test_cd_hle_boot test/test_cd_bios_boot; do
-    if [ ! -x "$bin" ]; then
+    if [ ! -x "$bin" ] || ! file "$bin" 2>/dev/null | grep -q executable; then
         echo "Building $bin..." >&2
-        make "$bin" || { echo "FATAL: failed to build $bin" >&2; exit 1; }
+        rm -f "$bin"
+        make TEST_EXPORTS=1 "$bin" || { echo "FATAL: failed to build $bin" >&2; exit 1; }
     fi
 done