Some memory fixes

[vikman90]

Hi,

I propose these changes, that should fix three issues detected from previous commits:

1. PR fix memory leak in decode-xml.c #930 prevents a memory leak by freeing pi structure, but pi->name should be deleted before.

2. At function 09e9f5b#diff-7c75ce14fc99e77cf2ac6208fbb99946R1233 a string is created and filled but it's not initialized. We'll write the last NULL character and declare the function as returning a constant string.

3. At PR fix common realloc mistake in custom_output_search_replace.c #931 a test to check that realloc returns a valid pointer is performed, but in case of error, old memory is freed and the loop continues using the variable pointing to an invalid address. os_realloc checks whether memory is available and if it isn't, will make the program to exit.

Best regards.