make Linux behavior default for loading Python shared lib

This adds portability to platforms like FreeBSD

python/lammps/mliap/__init__.py

@@ -4,15 +4,27 @@
 # try to improperly start up a new interpreter.
 import sysconfig
 import ctypes
-library = sysconfig.get_config_vars('INSTSONAME')[0]
+import platform
+import warnings
+
+py_ver = sysconfig.get_config_vars('VERSION')[0]
+OS_name = platform.system()
+
+if OS_name == "Darwin":
+    SHLIB_SUFFIX = '.dylib'
+    library = 'libpython' + py_ver + SHLIB_SUFFIX
+elif OS_name == "Windows":
+    SHLIB_SUFFIX = '.dll'
+    library = 'python' + py_ver + SHLIB_SUFFIX
+else:
+    SHLIB_SUFFIX = '.so'
+    library = 'libpython' + py_ver + SHLIB_SUFFIX
+
 try:
     pylib = ctypes.CDLL(library)
-except OSError as e:
-    if pylib.endswith(".a"):
-        pylib.strip(".a") + ".so"
-        pylib = ctypes.CDLL(library)
-    else:
-        raise e
+except Exception as e:
+    raise OSError("Unable to locate python shared library") from e
+
 if not pylib.Py_IsInitialized():
     raise RuntimeError("This interpreter is not compatible with python-based mliap for LAMMPS.")
 del sysconfig, ctypes, library, pylib