formats/format_wav: enhancing log message "Not a wav file" to be clear on what is supported

Modifying the log message to be more specific as to what is supported. Specifically it seems format_wav supports only PCM encoded versions with a lower-case '.wav' extension.

(closes issues ASTERISK-22310)
Reported by: Jim Credland
Review: https://reviewboard.asterisk.org/r/3188/
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Merged revisions 407511 from http://svn.asterisk.org/svn/asterisk/branches/1.8
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Merged revisions 407512 from http://svn.asterisk.org/svn/asterisk/branches/11
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Merged revisions 407513 from http://svn.asterisk.org/svn/asterisk/branches/12


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@407514 65c4cc65-6c06-0410-ace0-fbb531ad65f3

formats/format_wav.c

@@ -91,7 +91,7 @@ static int check_header_fmt(FILE *f, int hsize, int hz)
 		return -1;
 	}
 	if (ltohs(format) != 1) {
-		ast_log(LOG_WARNING, "Not a wav file %d\n", ltohs(format));
+		ast_log(LOG_WARNING, "Not a supported wav file format (%d). Only PCM encoded, 16 bit, mono, 8kHz files are supported with a lowercase '.wav' extension.\n", ltohs(format));
 		return -1;
 	}
 	if (fread(&chans, 1, 2, f) != 2) {