Revert std::malloc/std::free to global malloc/free (#4569) (#4570)

include/fmt/format.h

@@ -41,10 +41,11 @@
 #include "base.h"
 
 #ifndef FMT_MODULE
+#  include <stdlib.h>  // malloc, free
+
 #  include <cmath>    // std::signbit
 #  include <cstddef>  // std::byte
 #  include <cstdint>  // uint32_t
-#  include <cstdlib>  // std::malloc, std::free
 #  include <cstring>  // std::memcpy
 #  include <limits>   // std::numeric_limits
 #  include <new>      // std::bad_alloc
@@ -744,12 +745,12 @@ template <typename T> struct allocator : private std::decay<void> {
 
   auto allocate(size_t n) -> T* {
     FMT_ASSERT(n <= max_value<size_t>() / sizeof(T), "");
-    T* p = static_cast<T*>(std::malloc(n * sizeof(T)));
+    T* p = static_cast<T*>(malloc(n * sizeof(T)));
     if (!p) FMT_THROW(std::bad_alloc());
     return p;
   }
 
-  void deallocate(T* p, size_t) { std::free(p); }
+  void deallocate(T* p, size_t) { free(p); }
 
   constexpr friend auto operator==(allocator, allocator) noexcept -> bool {
     return true;  // All instances of this allocator are equivalent.