Bug #43414 Parenthesis (and other) warnings compiling MySQL

with gcc 4.3.2
      
This patch fixes a number of GCC warnings about variables used
before initialized. A new macro UNINIT_VAR() is introduced for
use in the variable declaration, and LINT_INIT() usage will be
gradually deprecated. (A workaround is used for g++, pending a
patch for a g++ bug.)
      
GCC warnings for unused results (attribute warn_unused_result)
for a number of system calls (present at least in later
Ubuntus, where the usual void cast trick doesn't work) are
also fixed.


client/mysqlmanager-pwgen.c:
  A fix for warn_unused_result, adding fallback to use of
  srand()/rand() if /dev/random cannot be used. Also actually
  adds calls to rand() in the second branch so that it actually
  creates a random password.

mysys/my_getopt.c

@@ -100,7 +100,7 @@ int handle_options(int *argc, char ***argv,
   uint opt_found, argvpos= 0, length, i;
   my_bool end_of_options= 0, must_be_var, set_maximum_value,
           option_is_loose;
-  char **pos, **pos_end, *optend, *prev_found,
+  char **pos, **pos_end, *optend, *UNINIT_VAR(prev_found),
        *opt_str, key_name[FN_REFLEN];
   const struct my_option *optp;
   gptr *value;