libcompat: Add missing ‘*’ in asprintf() and vasprintf() declarations

debian/changelog

@@ -42,6 +42,7 @@ dpkg (1.16.2) UNRELEASED; urgency=low
   * Stop using brace expansion to install man pages by using dh_installman
     instead of dh_install, the former does not abort on empty glob expansion.
   * Do not use absolute paths for programs in perl and shell code.
+  * Add missing ‘*’ in asprintf() and vasprintf() compat declarations.
 
   [ Raphaël Hertzog ]
   * Update Dpkg::Shlibs to look into multiarch paths when cross-building

lib/compat/compat.h

@@ -60,8 +60,8 @@ int vsnprintf(char *buf, size_t maxsize, const char *fmt, va_list args);
 #ifndef HAVE_ASPRINTF
 #include <stdarg.h>
 
-int asprintf(char *str, char const *fmt, ...);
-int vasprintf(char *str, const char *fmt, va_list args);
+int asprintf(char **str, char const *fmt, ...);
+int vasprintf(char **str, const char *fmt, va_list args);
 #endif
 
 #ifndef HAVE_STRNDUP