Fixes "incomplete type" complaints

cython always complaint about "incomplete type" for pthread_mutex_t
and sockaddr_storage.
They must be atleast defined with a "pass", which makes the complaint
go away.

Also reformat the imports a bit.

Author: tazend

UPGRADE_C_API.rst

@@ -51,13 +51,8 @@ Then, simply generate the header definitions like in this example:
     scripts/pyslurm_bindgen.py -D /directoy/with/slurm/headers > pyslurm/slurm/header.pxi
 
 The script outputs everything to `stdout`. Simply redirect the output to the file: :code:`pyslurm/slurm/header.pxi`.
+The headers should now be fully translated.
 
-Now, 99% of the work is done for generating the headers. For the 1% left, you now need to open the generated file, search for the two follwowing statements and comment them out:
-
-- `slurm_addr_t control_addr`
-- `phtread_mutex_t lock`
-
-The compiler will otherwise complain that these are incomplete type definitions.
 
 Compiling, Updating, Testing
 ----------------------------

pyslurm/slurm/__init__.pxd

@@ -1,19 +1,37 @@
 from libcpp cimport bool
-from posix.unistd cimport uid_t, pid_t, gid_t
-from libc.stdint cimport int8_t, int16_t, int32_t, int64_t
-from libc.stdint cimport uint8_t, uint16_t, uint32_t, uint64_t
 from cpython.version cimport PY_MAJOR_VERSION
-from libc.string cimport strlen, memcpy
 
-cdef extern from "<netinet/in.h>" nogil:
-    ctypedef struct sockaddr_in
-    ctypedef struct sockaddr_storage
+from posix.unistd cimport (
+    uid_t,
+    pid_t,
+    gid_t,
+)
+
+from libc.stdint cimport (
+    int8_t,
+    int16_t,
+    int32_t,
+    int64_t,
+    uint8_t,
+    uint16_t,
+    uint32_t,
+    uint64_t,
+)
+
+from libc.string cimport (
+    strlen,
+    memcpy,
+)
+
+cdef extern from '<netinet/in.h>' nogil:
+    ctypedef struct sockaddr_storage:
+        pass
 
 cdef extern from '<stdio.h>' nogil:
     ctypedef struct FILE
     cdef FILE *stdout
 
-cdef extern from 'time.h' nogil:
+cdef extern from '<time.h>' nogil:
     ctypedef long time_t
     double difftime(time_t time1, time_t time2)
     time_t time(time_t *t)
@@ -24,8 +42,15 @@ cdef extern from '<Python.h>' nogil:
     cdef int __LINE__
     char *__FUNCTION__
 
-cdef extern from "<pthread.h>" nogil:
-    ctypedef union pthread_mutex_t
+cdef extern from '<pthread.h>' nogil:
+    ctypedef struct pthread_mutex_t:
+        pass
+
+    ctypedef struct pthread_cond_t:
+        pass
+
+    ctypedef struct pthread_t:
+        pass
 
 cdef extern from *:
     ctypedef struct slurm_job_credential