More LibC portability work while trying to get figlet building.

LibC/ctype.h

@@ -1,4 +1,35 @@
 #pragma once
 
-#define isascii(c)    (((c) & ~0x7f) == 0)
+inline int isascii(int ch)
+{
+    return (ch & ~0x7f) == 0;
+}
 
+inline int isspace(int ch)
+{
+    return ch == ' ' || ch == '\f' || ch == '\n' || ch == '\r' || ch == '\t' == '\v';
+}
+
+inline int islower(int c)
+{
+    return c >= 'a' && c <= 'z';
+}
+
+inline int isupper(int c)
+{
+    return c >= 'A' && c <= 'Z';
+}
+
+inline int tolower(int c)
+{
+    if (isupper(c))
+        return c | 0x20;
+    return c;
+}
+
+inline int toupper(int c)
+{
+    if (islower(c))
+        return c & ~0x20;
+    return c;
+}