python: Fix configure generating setup.py.

* lang/python/setup.py.in: Handle the case, when substitutions
may be empty.

--

Reported-by: Andreas Metzler
Fixes-commit: ae9258fbf3
GnuPG-bug-id: 6204
Signed-off-by: NIIBE Yutaka <gniibe@fsij.org>

lang/python/setup.py.in

@@ -68,13 +68,17 @@ if not gpgme_h:
     gpgme_h = os.path.join('@prefix@', 'include', 'gpgme.h')
 
 define_macros = []
+if '@GPGME_CONFIG_LIBS@':
     libs = '@GPGME_CONFIG_LIBS@'.split(' ')
+else:
+    libs = []
 
 # Define extra_macros for both the SWIG and C code
 for k, v in extra_macros.items():
     extra_swig_opts.append('-D{0}={1}'.format(k, v))
     define_macros.append((k, str(v)))
 
+if '@GPGME_CONFIG_CFLAGS@':
     for item in '@GPGME_CONFIG_CFLAGS@'.split(' '):
         if item.startswith('-I'):
             include_dirs.append(item[2:])
@@ -165,8 +169,9 @@ class BuildExtFirstHack(build):
 
     def _generate_errors_i(self):
 
+        ge_cflags='@GPG_ERROR_CFLAGS@'
         gpg_error_content = self._read_header(
-            'gpg-error.h', '@GPG_ERROR_CFLAGS@'.split(' '))
+            'gpg-error.h', ge_cflags.split(' ') if ge_cflags else [])
 
         filter_re = re.compile(r'GPG_ERR_[^ ]* =')
         rewrite_re = re.compile(r' *(.*) = .*')