Update code style

Limit source code to 80 chars, and declare functions return type and
modifiers on a separate line.

This allows to avoid very long lines, and all function names are
aligned.

(We do this on VLC, and I like it.)

app/src/str_util.h

@@ -9,21 +9,25 @@
 //  - it does not write useless bytes if strlen(src) < n
 //  - it returns the number of chars actually written (max n-1) if src has
 //    been copied completely, or n if src has been truncated
-size_t xstrncpy(char *dest, const char *src, size_t n);
+size_t
+xstrncpy(char *dest, const char *src, size_t n);
 
 // join tokens by sep into dst
 // returns the number of chars actually written (max n-1) if no trucation
 // occurred, or n if truncated
-size_t xstrjoin(char *dst, const char *const tokens[], char sep, size_t n);
+size_t
+xstrjoin(char *dst, const char *const tokens[], char sep, size_t n);
 
 // quote a string
 // returns the new allocated string, to be freed by the caller
-char *strquote(const char *src);
+char *
+strquote(const char *src);
 
 #ifdef _WIN32
 // convert a UTF-8 string to a wchar_t string
 // returns the new allocated string, to be freed by the caller
-wchar_t *utf8_to_wide_char(const char *utf8);
+wchar_t *
+utf8_to_wide_char(const char *utf8);
 #endif
 
 #endif