gh-78630: Drop invalid HP aCC compiler switch -fPIC on HP-UX (GH-8847)

At compile time, '+z' is already properly used with HP aCC, and shared
libraries are correctly linked with '+b'. The '-fPIC' switch can safely be
dropped.
(cherry picked from commit 09be18a)

Co-authored-by: Michael Osipov <[email protected]>

Author: miss-islington

Misc/NEWS.d/next/Build/2018-08-21-11-10-18.bpo-34449.Z3qm3c.rst

@@ -0,0 +1 @@
+Drop invalid compiler switch ``-fPIC`` for HP aCC on HP-UX. Patch by Michael Osipov.

setup.py

@@ -1408,9 +1408,6 @@ def detect_ctypes(self):
             # finding some -z option for the Sun compiler.
             extra_link_args.append('-mimpure-text')
 
-        elif HOST_PLATFORM.startswith('hp-ux'):
-            extra_link_args.append('-fPIC')
-
         ext = Extension('_ctypes',
                         include_dirs=include_dirs,
                         extra_compile_args=extra_compile_args,