small improvment to formatter

include/spdlog/details/fmt_helper.h

@@ -16,8 +16,12 @@ inline void append_str(const std::string &str, fmt::memory_buffer &dest)
 
 inline void append_c_str(const char *c_str, fmt::memory_buffer &dest)
 {
-    auto str_size = strlen(c_str);
-    dest.append(c_str, c_str + str_size);
+    char ch;
+    while ((ch = *c_str) != '\0')
+    {
+        dest.push_back(ch);
+        ++c_str;
+    }
 }
 
 inline void append_buf(const fmt::memory_buffer &buf, fmt::memory_buffer &dest)

include/spdlog/details/pattern_formatter_impl.h

@@ -506,7 +506,6 @@ class full_formatter SPDLOG_FINAL : public flag_formatter
 #endif
 
         dest.push_back('[');
-
         // wrap the level name with color
         msg.color_range_start = dest.size();
         fmt_helper::append_c_str(level::to_str(msg.level), dest);