List cl_khr_icd_unloadable in correct place; NFC (#2661)

cl_khr_icd_unloadable is an API-only extension, so make sure it's in the
correct place in test_compiler's extension list.

This has no functional effect currently, because commit 5af0e74 ("Add
cl_khr_icd_unloadable to the list of known_extensions (#2605)",
2026-01-20) did not bump `first_API_extension` such that
cl_khr_icd_unloadable was already treated as an API-only extension.

Signed-off-by: Sven van Haastregt <sven.vanhaastregt@arm.com>

Author: svenvh

test_conformance/compiler/test_compiler_defines_for_extensions.cpp

@@ -56,10 +56,10 @@ const char *known_extensions[] = {
     "cl_khr_integer_dot_product",
     "cl_khr_subgroup_rotate",
     "cl_khr_kernel_clock",
-    "cl_khr_icd_unloadable",
     // API-only extensions after this point.  If you add above here, modify
     // first_API_extension below.
     "cl_khr_icd",
+    "cl_khr_icd_unloadable",
     "cl_khr_gl_sharing",
     "cl_khr_gl_event",
     "cl_khr_d3d10_sharing",