Hi,

When running GDB's testsuite with libraries/compilers that are more 
restrictive in terms of warnings, i've found that some tests were 
failing due to malloc being called but not having its return value 
assigned to any variables, leading to this warning:

warning: ignoring return value of 'malloc', declared with attribute 
warn_unused_result [-Wunused-result]

The following patch adjusts those testcases to silence the warnings by 
(1) assigning malloc's return value and (2) freeing that pointer later on.

In the case of gdb.base/randomize.c, we're missing a free call, which 
leads to an unused variable warning.

Ok?