[libc] Update generated libc header to include missing functions/files. (#163658)

* Add a missing dependency to install struct_itimerval.h
* Add fseeko/ftello declarations to stdio.h

Author: vonosmas

libc/include/CMakeLists.txt

@@ -632,8 +632,9 @@ add_header_macro(
   sys/time.h
   DEPENDS
     .llvm_libc_common_h
-    .llvm-libc-types.struct_timeval
     .llvm-libc-macros.sys_time_macros
+    .llvm-libc-types.struct_itimerval
+    .llvm-libc-types.struct_timeval
 )
 
 add_header_macro(

libc/include/stdio.yaml

@@ -197,12 +197,26 @@ functions:
       - type: FILE *
       - type: long
       - type: int
+  - name: fseeko
+    standards:
+      - POSIX
+    return_type: int
+    arguments:
+      - type: FILE *
+      - type: off_t
+      - type: int
   - name: ftell
     standards:
       - stdc
     return_type: long
     arguments:
       - type: FILE *
+  - name: ftello
+    standards:
+      - POSIX
+    return_type: off_t
+    arguments:
+      - type: FILE *
   - name: funlockfile
     standards:
       - POSIX