Update dr_libs.

extras/dr_flac.h

 /*
 FLAC audio decoder. Choice of public domain or MIT-0. See license statements at the end of this file.
-dr_flac - v0.12.25 - 2020-12-26
+dr_flac - v0.12.26 - 2021-01-17
 
 David Reid - mackron@gmail.com
 
@@ -232,7 +232,7 @@ extern "C" {
 
 #define DRFLAC_VERSION_MAJOR     0
 #define DRFLAC_VERSION_MINOR     12
-#define DRFLAC_VERSION_REVISION  25
+#define DRFLAC_VERSION_REVISION  26
 #define DRFLAC_VERSION_STRING    DRFLAC_XSTRINGIFY(DRFLAC_VERSION_MAJOR) "." DRFLAC_XSTRINGIFY(DRFLAC_VERSION_MINOR) "." DRFLAC_XSTRINGIFY(DRFLAC_VERSION_REVISION)
 
 #include <stddef.h> /* For size_t. */
@@ -1340,6 +1340,9 @@ DRFLAC_API drflac_bool32 drflac_next_cuesheet_track(drflac_cuesheet_track_iterat
     #ifndef _BSD_SOURCE
         #define _BSD_SOURCE
     #endif
+    #ifndef _DEFAULT_SOURCE
+        #define _DEFAULT_SOURCE
+    #endif
     #ifndef __USE_BSD
         #define __USE_BSD
     #endif
@@ -11802,6 +11805,9 @@ DRFLAC_API drflac_bool32 drflac_next_cuesheet_track(drflac_cuesheet_track_iterat
 /*
 REVISION HISTORY
 ================
+v0.12.26 - 2021-01-17
+  - Fix a compilation warning due to _BSD_SOURCE being deprecated.
+
 v0.12.25 - 2020-12-26
   - Update documentation.