test(libc): name the failing check in the exact math test

core/libs/tests/GuestMathExact.cpp

@@ -5,10 +5,16 @@
 #include <climits>
 #include <cmath>
 #include <cstdint>
+#include <cstdio>
 #include <cstdlib>
 #include <cstring>
+#include <source_location>
 
-static void Require(bool value) { if (!value) std::abort(); }
+static void Require(bool value, std::source_location location = std::source_location::current()) {
+    if (value) return;
+    std::fprintf(stderr, "%s:%u: requirement failed\n", location.file_name(), location.line());
+    std::abort();
+}
 
 [[gnu::noinline]] static long double Extended(std::uint16_t signExponent, std::uint64_t mantissa) {
     long double value = 0;