Update README.md (#3338)

How to install this package in ALT Linux.

README.md

@@ -36,6 +36,7 @@ see example [CMakeLists.txt](https://github.com/gabime/spdlog/blob/v1.x/example/
 * Gentoo: `emerge dev-libs/spdlog`
 * Arch Linux: `pacman -S spdlog`
 * openSUSE: `sudo zypper in spdlog-devel`
+* ALT Linux: `apt-get install libspdlog-devel`
 * vcpkg: `vcpkg install spdlog`
 * conan: `conan install --requires=spdlog/[*]`
 * conda: `conda install -c conda-forge spdlog`

include/spdlog/fmt/fmt.h

@@ -27,5 +27,4 @@
 #else  // SPDLOG_FMT_EXTERNAL is defined - use external fmtlib
     #include <fmt/core.h>
     #include <fmt/format.h>
-    #include <fmt/xchar.h>
 #endif

tests/test_daily_logger.cpp

@@ -46,12 +46,10 @@ TEST_CASE("daily_logger with dateonly calculator", "[daily_logger]") {
 
 struct custom_daily_file_name_calculator {
     static spdlog::filename_t calc_filename(const spdlog::filename_t &basename, const tm &now_tm) {
-        filename_memory_buf_t w;
+        
-        spdlog::fmt_lib::format_to(std::back_inserter(w), SPDLOG_FILENAME_T("{}{:04d}{:02d}{:02d}"),
+        return spdlog::fmt_lib::format(SPDLOG_FILENAME_T("{}{:04d}{:02d}{:02d}"),
                                    basename, now_tm.tm_year + 1900, now_tm.tm_mon + 1,
                                    now_tm.tm_mday);        
-
-        return SPDLOG_BUF_TO_STRING(w);
     }
 };