[stdlib] Use the single-header Glibc modulemap.

This migrates OpenBSD to use the single-header Glibc modulemap proposed
and implemented in #32404, and necessitates introducing some missing
headers for building Foundation added in #38341.

Additionally, incorporate nullability annotations in SwiftShims per

Author: 3405691582

stdlib/public/Platform/CMakeLists.txt

@@ -130,11 +130,7 @@ foreach(sdk ${SWIFT_SDKS})
     set(module_dir "${SWIFTLIB_DIR}/${arch_subdir}")
     set(module_dir_static "${SWIFTSTATICLIB_DIR}/${arch_subdir}")
 
-    if(${sdk} STREQUAL OPENBSD)
-      set(glibc_modulemap_source "libc-openbsd.modulemap.gyb")
-    else()
-      set(glibc_modulemap_source "glibc.modulemap.gyb")
-    endif()
+    set(glibc_modulemap_source "glibc.modulemap.gyb")
     set(glibc_modulemap_out "${module_dir}/glibc.modulemap")
     set(glibc_modulemap_out_static "${module_dir_static}/glibc.modulemap")
 

stdlib/public/Platform/SwiftGlibc.h.gyb

@@ -27,6 +27,7 @@ headers = [
   'string.h',
   'tgmath.h',
   'time.h',
+  'util.h',
   'utmp.h',
 
   # POSIX
@@ -69,6 +70,7 @@ headers = [
   'sys/ioctl.h',
   'sys/ipc.h',
   'sys/mman.h',
+  'sys/mount.h',
   'sys/msg.h',
   'sys/resource.h',
   'sys/select.h',

stdlib/public/Platform/glibc.modulemap.gyb

@@ -19,17 +19,19 @@
 /// It's not named just Glibc so that it doesn't conflict in the event of a
 /// future official glibc modulemap.
 module SwiftGlibc [system] {
-% if CMAKE_SDK in ["LINUX", "ANDROID"]:
+% if CMAKE_SDK in ["LINUX", "ANDROID", "OPENBSD"]:
       link "m"
 % end
-% if CMAKE_SDK in ["LINUX", "FREEBSD", "CYGWIN"]:
+% if CMAKE_SDK in ["LINUX", "FREEBSD", "OPENBSD", "CYGWIN"]:
   link "pthread"
   // FIXME: util contains rarely used functions and not usually needed. Unfortunately
   // link directive doesn't work in the submodule yet.
+% if CMAKE_SDK != "OPENBSD":
   link "util"
 % end
+% end
 
-% if CMAKE_SDK != "FREEBSD" and CMAKE_SDK != "HAIKU":
+% if CMAKE_SDK not in ["FREEBSD", "OPENBSD", "HAIKU"]:
   link "dl"
 % end
 

stdlib/public/Platform/libc-openbsd.modulemap.gyb

@@ -60,7 +60,7 @@ static inline __swift_size_t _swift_stdlib_strlen_unsigned(const unsigned char *
 SWIFT_READONLY
 static inline int _swift_stdlib_memcmp(const void *s1, const void *s2,
                                        __swift_size_t n) {
-#if defined(__APPLE__) || defined(__ANDROID__)
+#if defined(__APPLE__) || defined(__ANDROID__) || defined(__OpenBSD__)
   extern int memcmp(const void * _Nullable, const void * _Nullable, __swift_size_t);
 #else
   extern int memcmp(const void *, const void *, __swift_size_t);