[libc] final edits to newheadergen yaml files

Performed one last run of integration tests, removing duplicate types
and removing unneeded files.
Currently looked through all sys files, will finish checking other yaml
files this week.

Author: RoseZhang03

libc/newhdrgen/yaml/sys/sys_time.yaml

@@ -1,8 +1,7 @@
 header: sys-time.h
 standards: Linux
 macros: []
-types:
-  - type_name: struct_timeval
+types: []
 enums: []
 functions: []
 objects: []