Fix MSVC CRT for Unit tests

Author: solidpixel

Source/UnitTest/cmake_core.cmake

@@ -27,6 +27,11 @@ if(${ASTCENC_CLI})
             INTERPROCEDURAL_OPTIMIZATION_RELEASE True)
 endif()
 
+# Use a static runtime on MSVC builds (ignored on non-MSVC compilers)
+set_property(TARGET ${ASTCENC_TEST}
+    PROPERTY
+        MSVC_RUNTIME_LIBRARY "MultiThreaded$<$<CONFIG:Debug>:Debug>")
+
 target_sources(${ASTCENC_TEST}
     PRIVATE
         test_simd.cpp