restructuring classic snippets dir to conform to new parenting specs

snippets/c-mode/.yas-parents

@@ -0,0 +1 @@
+cc-mode

snippets/c-mode/fopen

@@ -0,0 +1,3 @@
+#name : FILE *fp = fopen(..., ...);
+# --
+FILE *${fp} = fopen(${"file"}, "${r}");

snippets/c-mode/printf

@@ -0,0 +1,6 @@
+# -*- mode: snippet -*-
+# name : printf 
+# contributor : joaotavora
+# --
+printf ("${1:%s}\\n"${1:$(if (string-match "%" text) "," "\);")
+}$2${1:$(if (string-match "%" text) "\);" "")}