Added proposed upstream patch with Big Endian fixes.

fmt-big-endian-fixes.patch

@@ -0,0 +1,36 @@
+From 0273005bf5e92f1bbf230b654939489b01eb2eb3 Mon Sep 17 00:00:00 2001
+From: Vladislav Shchapov <phprus@gmail.com>
+Date: Tue, 4 Jan 2022 15:04:30 +0500
+Subject: [PATCH] Fix endianness bug in write_digit2_separated
+
+---
+ include/fmt/chrono.h | 16 ++++++++++++++++
+ 1 file changed, 16 insertions(+)
+
+diff --git a/include/fmt/chrono.h b/include/fmt/chrono.h
+index 908999ab5f..c52be81ca6 100644
+--- a/include/fmt/chrono.h
++++ b/include/fmt/chrono.h
+@@ -558,6 +558,22 @@ inline void write_digit2_separated(char* buf, unsigned a, unsigned b,
+   auto usep = static_cast<unsigned long long>(sep);
+   // Add ASCII '0' to each digit byte and insert separators.
+   digits |= 0x3030003030003030 | (usep << 16) | (usep << 40);
++#ifndef _WIN32
++#  if defined(__GNUC__) && __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
++  digits = __builtin_bswap64(digits);
++#  else
++  if (is_big_endian()) {
++    digits = ((digits & 0xff00000000000000ull) >> 56) |
++             ((digits & 0x00ff000000000000ull) >> 40) |
++             ((digits & 0x0000ff0000000000ull) >> 24) |
++             ((digits & 0x000000ff00000000ull) >> 8) |
++             ((digits & 0x00000000ff000000ull) << 8) |
++             ((digits & 0x0000000000ff0000ull) << 24) |
++             ((digits & 0x000000000000ff00ull) << 40) |
++             ((digits & 0x00000000000000ffull) << 56);
++  }
++#  endif
++#endif
+   memcpy(buf, &digits, 8);
+ }
+ 

fmt.spec

@@ -9,6 +9,9 @@ Summary:        Small, safe and fast formatting library for C++
 URL:            https://github.com/fmtlib/%{name}
 Source0:        %{url}/archive/%{version}.tar.gz
 
+# https://github.com/fmtlib/fmt/pull/2699
+Patch100:       %{name}-big-endian-fixes.patch
+
 BuildRequires:  gcc
 BuildRequires:  gcc-c++
 BuildRequires:  ninja-build