Fix signed char arg parsing. (fix by Frédéric Bastien)

pyopencl/tools.py

@@ -232,7 +232,7 @@ def parse_c_arg(c_arg):
         dtype = np.uint64
     elif tp in ["short", "short int"]: dtype = np.int16
     elif tp in ["unsigned short", "unsigned short int"]: dtype = np.uint16
-    elif tp in ["char"]: dtype = np.int8
+    elif tp in ["char", "signed char"]: dtype = np.int8
     elif tp in ["unsigned char"]: dtype = np.uint8
     elif tp in ["bool"]: dtype = np.bool
     else: