Some wrong options silently ignored if starting with same letters as valid option

For example, options below are silently "accepted"+ignored:
  valgrind --profile-heaps=yes --max-stackframes=35 memcheck/tests/trivialleak
  valgrind --profile-heaps=oui --max-stackframes=3.141592654 memcheck/tests/trivialleak

Also fixed the on-line --help output for option --core-redzone-size



git-svn-id: svn://svn.valgrind.org/valgrind/trunk@13037 a5019735-40e9-0310-863c-91ae7b9d1cf9
diff --git a/NEWS b/NEWS
index 2f8760b..81d0031 100644
--- a/NEWS
+++ b/NEWS
@@ -33,6 +33,7 @@
 306054    [390] s390x: Condition code computation for convert-to-int/logical
 307155    [390] filter_gdb should filter out syscall-template.S T_PSEUDO
 n-i-bz    [390] report error for vgdb snapshot requested before execution
+n-i-bz    [390] Some wrong command line options could be ignored
 
 Release 3.8.1 (19 September 2012)
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~