patch 7.4.1793
Problem:    Some character classes may differ between systems.  On OS/X the
            regexp test fails.
Solution:   Make this less dependent on the system. (idea by Kazunobu Kuriyama)
diff --git a/src/regexp.c b/src/regexp.c
index 733d564..5f1fc1c 100644
--- a/src/regexp.c
+++ b/src/regexp.c
@@ -2542,12 +2542,12 @@
 				}
 				break;
 			    case CLASS_ALNUM:
-				for (cu = 1; cu <= 255; cu++)
+				for (cu = 1; cu < 128; cu++)
 				    if (isalnum(cu))
 					regmbc(cu);
 				break;
 			    case CLASS_ALPHA:
-				for (cu = 1; cu <= 255; cu++)
+				for (cu = 1; cu < 128; cu++)
 				    if (isalpha(cu))
 					regmbc(cu);
 				break;
@@ -2572,7 +2572,8 @@
 				break;
 			    case CLASS_LOWER:
 				for (cu = 1; cu <= 255; cu++)
-				    if (MB_ISLOWER(cu))
+				    if (MB_ISLOWER(cu) && cu != 170
+								 && cu != 186)
 					regmbc(cu);
 				break;
 			    case CLASS_PRINT:
@@ -2581,7 +2582,7 @@
 					regmbc(cu);
 				break;
 			    case CLASS_PUNCT:
-				for (cu = 1; cu <= 255; cu++)
+				for (cu = 1; cu < 128; cu++)
 				    if (ispunct(cu))
 					regmbc(cu);
 				break;