fix(scap): Potential leak of memory pointed to by 'heap_tinfo'

```
/code/falcosecurity/libs/userspace/libscap/scap_procs.c:144:11: warning: Potential leak of memory pointed to by 'heap_tinfo' [clang-analyzer-unix.Malloc]
                        return scap_errprintf(error, errno, "can't allocate procinfo struct");
                               ^
/code/falcosecurity/libs/userspace/libscap/strerror.h:30:24: note: expanded from macro 'scap_errprintf'
                       ^
/code/falcosecurity/libs/userspace/libscap/scap_procs.c:82:5: note: Assuming 'fdinfo' is equal to NULL
        if(fdinfo != NULL)
           ^~~~~~~~~~~~~~
/code/falcosecurity/libs/userspace/libscap/scap_procs.c:82:2: note: Taking false branch
        if(fdinfo != NULL)
        ^
/code/falcosecurity/libs/userspace/libscap/scap_procs.c:141:33: note: Memory is allocated
                scap_threadinfo *heap_tinfo = malloc(sizeof(*heap_tinfo));
                                              ^~~~~~~~~~~~~~~~~~~~~~~~~~~
/code/falcosecurity/libs/userspace/libscap/scap_procs.c:142:6: note: Assuming 'tinfo' is equal to NULL
                if(tinfo == NULL)
                   ^~~~~~~~~~~~~
/code/falcosecurity/libs/userspace/libscap/scap_procs.c:142:3: note: Taking true branch
                if(tinfo == NULL)
                ^
/code/falcosecurity/libs/userspace/libscap/scap_procs.c:144:11: note: Potential leak of memory pointed to by 'heap_tinfo'
                        return scap_errprintf(error, errno, "can't allocate procinfo struct");
                               ^
```

Signed-off-by: Angelo Puglisi <angelopuglisi86@gmail.com>

userspace/libscap/scap_procs.c

@@ -139,7 +139,7 @@ int32_t default_proc_entry_callback(void* context, char* error, int64_t tid, sca
 		// add a thread
 		// get a copy of tinfo on the heap
 		scap_threadinfo *heap_tinfo = malloc(sizeof(*heap_tinfo));
-		if(tinfo == NULL)
+		if(heap_tinfo == NULL)
 		{
 			return scap_errprintf(error, errno, "can't allocate procinfo struct");
 		}