Warning for shadowed parameter corrected in common.h

However, not in bundled fmt. Corrects compiling with basic logger with header only and -Werror.

include/spdlog/common.h

@@ -210,10 +210,10 @@ struct source_loc
         , funcname{""}
     {
     }
-    SPDLOG_CONSTEXPR source_loc(const char *filename, int line, const char *funcname)
-        : filename{filename}
-        , line{static_cast<uint32_t>(line)}
-        , funcname{funcname}
+    SPDLOG_CONSTEXPR source_loc(const char *t_filename, int t_line, const char *t_funcname)
+        : filename{t_filename}
+        , line{static_cast<uint32_t>(t_line)}
+        , funcname{t_funcname}
     {
     }