add two tests

test/stralloc_buffer.c

@@ -0,0 +1,10 @@
+#include "stralloc.h"
+#include "buffer.h"
+
+main() {
+  static stralloc sa;
+  if (buffer_get_token_sa(buffer_0,&sa," \t\n",3)==0) {
+    buffer_putsa(buffer_1,&sa);
+    buffer_putnlflush(buffer_1);
+  }
+}

test/stralloc_chomp.c

@@ -0,0 +1,15 @@
+#include <assert.h>
+#include "stralloc.h"
+#include "buffer.h"
+
+main() {
+  static stralloc sa;
+  stralloc_copys(&sa,"foo\r\n");
+  assert(sa.len==5);
+  assert(stralloc_chomp(&sa)==2);
+  assert(stralloc_chop(&sa)=='o');
+  assert(stralloc_chop(&sa)=='o');
+  assert(stralloc_chop(&sa)=='f');
+  assert(stralloc_chop(&sa)==-1);
+  return 0;
+}