cmake: accommodate for UNIT_TEST_SOURCES

As part of 9340e7c (t/unit-tests: finalize migration of reftable-related
tests, 2025-06-05), the explicit list of `UNIT_TEST_PROGRAMS` was turned
into a wildcard pattern-derived list.

Let's do the same in the CMake definition.

This fixes build errors with symptoms like this:

  CMake Error at CMakeLists.txt:132 (string):
    string sub-command REPLACE requires at least four arguments.
  Call Stack (most recent call first):
    CMakeLists.txt:1037 (parse_makefile_for_scripts)

Signed-off-by: Johannes Schindelin <[email protected]>

Author: dscho

contrib/buildsystems/CMakeLists.txt

@@ -1034,7 +1034,9 @@ parse_makefile_for_sources(clar-test_SOURCES ${CMAKE_SOURCE_DIR}/Makefile "CLAR_
 list(TRANSFORM clar-test_SOURCES REPLACE "\\$\\(UNIT_TEST_DIR\\)/" "${CMAKE_SOURCE_DIR}/t/unit-tests/")
 add_library(clar-test-lib STATIC ${clar-test_SOURCES})
 
-parse_makefile_for_scripts(unit_test_PROGRAMS "UNIT_TEST_PROGRAMS" "")
+file(GLOB unit_test_PROGRAMS "${CMAKE_SOURCE_DIR}/t/unit-tests/t-*.c")
+list(TRANSFORM unit_test_PROGRAMS REPLACE "${CMAKE_SOURCE_DIR}/" "")
+list(TRANSFORM unit_test_PROGRAMS REPLACE ".c" "")
 foreach(unit_test ${unit_test_PROGRAMS})
 	add_executable("${unit_test}" "${CMAKE_SOURCE_DIR}/t/unit-tests/${unit_test}.c")
 	target_link_libraries("${unit_test}" unit-test-lib clar-test-lib common-main)