Better error reporting for python binding (#1188)

To diagnose issue with oss-fuzz building corpus
diff --git a/bindings/python/capstone/__init__.py b/bindings/python/capstone/__init__.py
index 08b68ef..ec8a9ff 100644
--- a/bindings/python/capstone/__init__.py
+++ b/bindings/python/capstone/__init__.py
@@ -216,16 +216,14 @@
 def _load_lib(path):
     lib_file = join(path, _lib)
     #print("Trying to load %s" %lib_file)
-    try:
+    if os.path.exists(lib_file):
         return ctypes.cdll.LoadLibrary(lib_file)
-    except OSError:
+    else:
         # if we're on linux, try again with .so.3 extension
         if lib_file.endswith('.so'):
-            try:
+            if os.path.exists(lib_file + '.3'):
                 return ctypes.cdll.LoadLibrary(lib_file + '.3')
-            except OSError:
-                return None
-        return None
+    return None
 
 _cs = None