[PATCH] libstdc++: Decouple HAVE_FCNTL_H from HAVE_DIRENT_H check

[Dimitar Dimitrov]

On PRU target with newlib, we have the following combination in config.h:
  /* #undef HAVE_DIRENT_H */
  #define HAVE_FCNTL_H 1
  #define HAVE_UNLINKAT 1

In newlib, targets which do not define dirent.h, get a build error when
including <dirent.h>:
  https://sourceware.org/git/?p=newlib-cygwin.git;a=blob;f=newlib/libc/include/sys/dirent.h;hb=HEAD

While fs_dir.cc correctly checks for HAVE_FCNTL_H, dir-common.h doesn't,
and instead uses HAVE_DIRENT_H. This results in unlinkat() function call
in fs_dir.cc without the needed <fcntl.h> include in dir-common.h. Thus
a build failure:
  .../gcc/libstdc++-v3/src/c++17/fs_dir.cc:151:11: error: ‘::unlinkat’ has not been declared; did you mean ‘unlink’?

Fix by encapsulating <fcntl.h> include with the correct check.

Regtested x86_64-pc-linux-gnu and no new failures detected.

Fixes commit r12-7062-gebf61754647689 (libstdc++: Fix filesystem::remove_all races).

libstdc++-v3/ChangeLog:

	* src/filesystem/dir-common.h (_GLIBCXX_HAVE_FCNTL_H): Move the
	check outside the HAVE_DIRENT_H check.

Signed-off-by: Dimitar Dimitrov <dimitar@dinux.eu>
---
 libstdc++-v3/src/filesystem/dir-common.h | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/libstdc++-v3/src/filesystem/dir-common.h b/libstdc++-v3/src/filesystem/dir-common.h
index 0b7665a3f70..cfce4fae9a4 100644
--- a/libstdc++-v3/src/filesystem/dir-common.h
+++ b/libstdc++-v3/src/filesystem/dir-common.h
@@ -35,10 +35,11 @@
 #  include <sys/types.h>
 # endif
 # include <dirent.h> // opendir, readdir, fdopendir, dirfd
-# ifdef _GLIBCXX_HAVE_FCNTL_H
-#  include <fcntl.h>  // open, openat, fcntl, AT_FDCWD, O_NOFOLLOW etc.
-#  include <unistd.h> // close, unlinkat
-# endif
+#endif
+
+#ifdef _GLIBCXX_HAVE_FCNTL_H
+# include <fcntl.h>  // open, openat, fcntl, AT_FDCWD, O_NOFOLLOW etc.
+# include <unistd.h> // close, unlinkat
 #endif
 
 namespace std _GLIBCXX_VISIBILITY(default)
-- 
2.34.1