Fix for libast sfstrtof() (Solaris patch 075-multi_lang_arith)

This change is pulled from here:
https://github.com/oracle/solaris-userland/blob/master/components/ksh93/patches/075-multi_lang_arith.patch

It appears to be a fix for converting a string to a floating point
value in certain locales. Unfortunately there is no publicly
available documentation on what it does exactly. We just have to
assume the Solaris people knew what they were doing.

src/lib/libast/sfio/sfstrtof.h

@@ -414,7 +414,7 @@ S2F_function(str, end) char* str; char** end;
 			m = 0;
 			fraction = digits;
 		}
-		else if (c != thousand)
+		else if (c != thousand || (c == thousand && decimal == -1))
 			break;
 		else if (!(m = digits))
 		{