Workaround C complex.h idiocy

test/core-test.cc

@@ -9,9 +9,7 @@
 #include "test-assert.h"
 // clang-format on
 
-#define I 42  // simulate https://en.cppreference.com/w/c/numeric/complex/I
 #include "fmt/core.h"
-#undef I
 
 #include <algorithm>    // std::copy_n
 #include <climits>      // INT_MAX

test/enforce-checks-test.cc

@@ -8,12 +8,14 @@
 #include <iterator>
 #include <vector>
 
+#define I 42  // simulate https://en.cppreference.com/w/c/numeric/complex/I
 #include "fmt/chrono.h"
 #include "fmt/color.h"
 #include "fmt/format.h"
 #include "fmt/ostream.h"
 #include "fmt/ranges.h"
 #include "fmt/xchar.h"
+#undef I
 
 // Exercise the API to verify that everything we expect to can compile.
 void test_format_api() {