meta: move photon/libc to root

libc/string/strcspn.c

@@ -0,0 +1,15 @@
+#include <stddef.h>
+
+size_t strcspn(const char *str1, const char *str2)
+{
+    size_t i;
+    for (i = 0; str1[i]; i++) {
+        for (size_t ii = 0; str2[ii]; ii++) {
+            if (str1[i] == str2[ii]) {
+                return i;
+            }
+        }
+    }
+
+    return i;
+}