The pure C test works again.

src/ctest/CMakeLists.txt

@@ -0,0 +1,2 @@
+add_executable(ctest main.c)
+target_link_libraries(ctest PRIVATE astaroth_core m)

src/ctest/main.c

@@ -0,0 +1,18 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "astaroth.h"
+
+int
+main(void)
+{
+    AcMeshInfo info = {
+        .int_params[AC_nx] = 128,
+        .int_params[AC_ny] = 64,
+        .int_params[AC_nz] = 32,
+    };
+    acInit(info);
+    acIntegrate(0.1f);
+    acQuit();
+    return EXIT_SUCCESS;
+}