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.

include/my_global.h

@@ -464,6 +464,19 @@ int	__void__;
 #define PURIFY_OR_LINT_INIT(var)
 #endif
 
+/* 
+   Suppress uninitialized variable warning without generating code.
+
+   The _cplusplus is a temporary workaround for C++ code pending a fix
+   for a g++ bug (http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34772). 
+*/
+#if defined(_lint) || defined(FORCE_INIT_OF_VARS) || defined(__cplusplus) || \
+  !defined(__GNUC__)
+#define UNINIT_VAR(x) x= 0
+#else
+#define UNINIT_VAR(x) x= x
+#endif
+
 /* Define some useful general macros */
 #if !defined(max)
 #define max(a, b)	((a) > (b) ? (a) : (b))