[libc] Use relative inclusion for public headers. (#114324)

We are finalizing the header inclusion policy, and for our public
headers in the `libc/include` folder, they must use relative path in
`"..."` when including each other.

This PR does the cleanup making sure that all the public header
inclusions in `libc/include` folder use relative paths.

---------

Co-authored-by: Nick Desaulniers <[email protected]>

Author: lntue

libc/include/gpu/rpc.h.def

@@ -11,7 +11,7 @@
 
 #include "__llvm-libc-common.h"
 
-#include "llvm-libc-types/rpc_opcodes_t.h"
+#include "../llvm-libc-types/rpc_opcodes_t.h"
 
 %%public_api()
 

libc/include/llvm-libc-macros/containerof-macro.h

@@ -9,7 +9,7 @@
 #ifndef LLVM_LIBC_MACROS_CONTAINEROF_MACRO_H
 #define LLVM_LIBC_MACROS_CONTAINEROF_MACRO_H
 
-#include "llvm-libc-macros/offsetof-macro.h"
+#include "offsetof-macro.h"
 
 #define __containerof(ptr, type, member)                                       \
   ({                                                                           \

libc/include/llvm-libc-macros/sys-queue-macros.h

@@ -9,8 +9,8 @@
 #ifndef LLVM_LIBC_MACROS_SYS_QUEUE_MACROS_H
 #define LLVM_LIBC_MACROS_SYS_QUEUE_MACROS_H
 
-#include "llvm-libc-macros/containerof-macro.h"
-#include "llvm-libc-macros/null-macro.h"
+#include "containerof-macro.h"
+#include "null-macro.h"
 
 #ifdef __cplusplus
 #define QUEUE_TYPEOF(type) type

libc/include/llvm-libc-types/__mutex_type.h

@@ -9,7 +9,7 @@
 #ifndef LLVM_LIBC_TYPES___MUTEX_TYPE_H
 #define LLVM_LIBC_TYPES___MUTEX_TYPE_H
 
-#include "llvm-libc-types/__futex_word.h"
+#include "__futex_word.h"
 
 typedef struct {
   unsigned char __timed;

libc/include/llvm-libc-types/cnd_t.h

@@ -9,7 +9,7 @@
 #ifndef LLVM_LIBC_TYPES_CND_T_H
 #define LLVM_LIBC_TYPES_CND_T_H
 
-#include "llvm-libc-types/__futex_word.h"
+#include "__futex_word.h"
 
 typedef struct {
   void *__qfront;

libc/include/llvm-libc-types/cookie_io_functions_t.h

@@ -9,9 +9,9 @@
 #ifndef LLVM_LIBC_TYPES_COOKIE_IO_FUNCTIONS_T_H
 #define LLVM_LIBC_TYPES_COOKIE_IO_FUNCTIONS_T_H
 
-#include "llvm-libc-types/off64_t.h"
-#include "llvm-libc-types/size_t.h"
-#include "llvm-libc-types/ssize_t.h"
+#include "off64_t.h"
+#include "size_t.h"
+#include "ssize_t.h"
 
 typedef ssize_t cookie_read_function_t(void *, char *, size_t);
 typedef ssize_t cookie_write_function_t(void *, const char *, size_t);

libc/include/llvm-libc-types/fd_set.h

@@ -9,7 +9,7 @@
 #ifndef LLVM_LIBC_TYPES_FD_SET_H
 #define LLVM_LIBC_TYPES_FD_SET_H
 
-#include "llvm-libc-macros/sys-select-macros.h" // FD_SETSIZE
+#include "../llvm-libc-macros/sys-select-macros.h" // __FD_SET_WORD_TYPE, __FD_SET_ARRAYSIZE
 
 typedef struct {
   __FD_SET_WORD_TYPE __set[__FD_SET_ARRAYSIZE];

libc/include/llvm-libc-types/mtx_t.h

@@ -9,7 +9,7 @@
 #ifndef LLVM_LIBC_TYPES_MTX_T_H
 #define LLVM_LIBC_TYPES_MTX_T_H
 
-#include "llvm-libc-types/__mutex_type.h"
+#include "__mutex_type.h"
 
 typedef __mutex_type mtx_t;
 

libc/include/llvm-libc-types/once_flag.h

@@ -9,7 +9,7 @@
 #ifndef LLVM_LIBC_TYPES_ONCE_FLAG_H
 #define LLVM_LIBC_TYPES_ONCE_FLAG_H
 
-#include "llvm-libc-types/__futex_word.h"
+#include "__futex_word.h"
 
 #ifdef __linux__
 typedef __futex_word once_flag;

libc/include/llvm-libc-types/pthread_attr_t.h

@@ -9,7 +9,7 @@
 #ifndef LLVM_LIBC_TYPES_PTHREAD_ATTR_T_H
 #define LLVM_LIBC_TYPES_PTHREAD_ATTR_T_H
 
-#include "llvm-libc-types/size_t.h"
+#include "size_t.h"
 
 typedef struct {
   int __detachstate;