Use angle brackes for posix includes.

Cython/Includes/posix/dlfcn.pxd

 # POSIX dynamic linking/loading interface.
 # http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/dlfcn.h.html
 
-cdef extern from "dlfcn.h" nogil:
+cdef extern from "<dlfcn.h>" nogil:
     void *dlopen(const char *, int)
     char *dlerror()
     void *dlsym(void *, const char *)

Cython/Includes/posix/fcntl.pxd

 # http://www.opengroup.org/onlinepubs/009695399/basedefs/fcntl.h.html
 
-cdef extern from "fcntl.h" nogil:
+cdef extern from "<fcntl.h>" nogil:
 
     enum: F_DUPFD
     enum: F_GETFD

Cython/Includes/posix/ioctl.pxd

-cdef extern from "sys/ioctl.h" nogil:
+cdef extern from "<sys/ioctl.h>" nogil:
     enum: FIONBIO
 
     int ioctl(int fd, int request, ...)

Cython/Includes/posix/mman.pxd

@@ -2,7 +2,7 @@
 
 from posix.types cimport off_t, mode_t
 
-cdef extern from "sys/mman.h" nogil:
+cdef extern from "<sys/mman.h>" nogil:
     enum: PROT_EXEC                 # protection bits for mmap/mprotect
     enum: PROT_READ
     enum: PROT_WRITE

Cython/Includes/posix/resource.pxd

@@ -3,7 +3,7 @@
 from posix.time  cimport timeval
 from posix.types cimport id_t
 
-cdef extern from "sys/resource.h" nogil:
+cdef extern from "<sys/resource.h>" nogil:
 
     enum: PRIO_PROCESS
     enum: PRIO_PGRP

Cython/Includes/posix/select.pxd

 from .types cimport sigset_t
 from .time cimport timeval, timespec
 
-cdef extern from "sys/select.h" nogil:
+cdef extern from "<sys/select.h>" nogil:
     ctypedef struct fd_set:
         pass
 

Cython/Includes/posix/signal.pxd

@@ -2,7 +2,7 @@
 
 from posix.types cimport pid_t, sigset_t, uid_t
 
-cdef extern from "signal.h" nogil:
+cdef extern from "<signal.h>" nogil:
 
     cdef union sigval:
         int  sival_int

Cython/Includes/posix/stat.pxd

@@ -2,7 +2,7 @@ from posix.types cimport (blkcnt_t, blksize_t, dev_t, gid_t, ino_t, mode_t,
                           nlink_t, off_t, time_t, uid_t)
 
 
-cdef extern from "sys/stat.h" nogil:
+cdef extern from "<sys/stat.h>" nogil:
     cdef struct struct_stat "stat":
         dev_t   st_dev
         ino_t   st_ino
@@ -19,7 +19,7 @@ cdef extern from "sys/stat.h" nogil:
         time_t  st_ctime
 
 # POSIX prescribes including both <sys/stat.h> and <unistd.h> for these
-cdef extern from "unistd.h" nogil:
+cdef extern from "<unistd.h>" nogil:
     int fchmod(int, mode_t)
     int chmod(const char *, mode_t)
 

Cython/Includes/posix/stdio.pxd

@@ -5,7 +5,7 @@ from libc.stdio cimport FILE
 from libc.stddef cimport wchar_t
 from posix.types cimport off_t
 
-cdef extern from "stdio.h" nogil:
+cdef extern from "<stdio.h>" nogil:
     # File descriptors
     FILE *fdopen(int, const char *)
     int fileno(FILE *)

Cython/Includes/posix/stdlib.pxd

 # POSIX additions to <stdlib.h>
 # http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/stdlib.h.html
 
-cdef extern from "stdlib.h" nogil:
+cdef extern from "<stdlib.h>" nogil:
     void   _Exit(int)
     double drand48()
     double erand48(unsigned short *)

Cython/Includes/posix/strings.pxd

-cdef extern from "strings.h" nogil:
+cdef extern from "<strings.h>" nogil:
     int    bcmp(const void *, const void *, size_t)
     void   bcopy(const void *, void *, size_t)
     void   bzero(void *, size_t)

Cython/Includes/posix/time.pxd

@@ -3,7 +3,7 @@
 from posix.types cimport suseconds_t, time_t, clockid_t, timer_t
 from posix.signal cimport sigevent
 
-cdef extern from "sys/time.h" nogil:
+cdef extern from "<sys/time.h>" nogil:
     enum: CLOCK_PROCESS_CPUTIME_ID
     enum: CLOCK_THREAD_CPUTIME_ID
 

Cython/Includes/posix/types.pxd

@@ -10,7 +10,7 @@
 # the POSIX standard doesn't even specify that time_t must be an integral
 # type).
 
-cdef extern from "sys/types.h":
+cdef extern from "<sys/types.h>":
     ctypedef long blkcnt_t
     ctypedef long blksize_t
     ctypedef long clockid_t

Cython/Includes/posix/unistd.pxd

@@ -2,7 +2,7 @@
 
 from posix.types cimport gid_t, pid_t, off_t, uid_t
 
-cdef extern from "unistd.h" nogil:
+cdef extern from "<unistd.h>" nogil:
 
     #:NULL
 

Cython/Includes/posix/wait.pxd

@@ -4,7 +4,7 @@ from posix.types cimport pid_t, id_t
 from posix.signal cimport siginfo_t
 from posix.resource cimport rusage
 
-cdef extern from "sys/wait.h" nogil:
+cdef extern from "<sys/wait.h>" nogil:
     enum: WNOHANG
     enum: WUNTRACED
     enum: WCONTINUED