Fixed a semantic error concerning ISO C99 Uninitialized Value Undefined Behaviour in Eva main manual

En lisant la doc d'Eva, page 19:

"Reading an initialized value is an undefined behavior according to the ISO C99 standard (and can even lead to security vulnerabilities)."

vs

"Reading an UNinitialized value is an undefined behavioraccording to the ISO C99 standard (and can even lead to security vulnerabilities)."

src/plugins/wp/configure.ac

@@ -50,14 +50,15 @@ plugin_use(wp,gui)
 ######################
 
 configure_pkg(why3,[package why3 not found])
+plugin_require_external(wp,why3)
 
-AC_MSG_CHECKING(why3 version)
 WHY3VERSION=`ocamlfind query -format %v why3 | tr -d '\\r\\n'`
-case $WHY3VERSION in
-      "")
-        AC_MSG_RESULT([not found!])
-        plugin_disable(wp,[why3 not found])
-        ;;
+if test "$WHY3VERSION" == "" ;
+then
+  plugin_disable(wp,[why3 not found])
+else
+  AC_MSG_CHECKING(why3 version)
+  case $WHY3VERSION in
       0.* | 1.[[012]].* | 1.3.0)
         AC_MSG_RESULT([found $WHY3VERSION: requires 1.3.1+])
         plugin_disable(wp,[non-supported why3 $WHY3VERSION])
@@ -68,13 +69,8 @@ case $WHY3VERSION in
       *)
         AC_MSG_RESULT([found $WHY3VERSION: might work (should be 1.3.1+)])
         ;;
-esac
-
-plugin_require_external(wp,why3)
-
-check_plugin_dependencies
-
-AC_SUBST(HAS_WHY3)
+  esac
+fi
 
 # Nb: this would deserve to use plugin_requires mechanism
 if test "$ENABLE_WP" != "no"; then