Fix README and segmentation fault for FreeBSD, addressing #163

Author: juzeon

README.md

@@ -236,7 +236,7 @@ curl -L https://gitee.com/RubyMetric/chsrc/releases/download/pre/chsrc-x64-macos
 
 ```bash
 $ git clone https://gitee.com/RubyMetric/chsrc.git; cd chsrc
-$ clang -Iinclude src/chsrc-main.c -o chsrc
+$ clang -Iinclude -Ilib src/chsrc-main.c -o chsrc
 ```
 </details>
 

lib/xy.h

@@ -642,7 +642,7 @@ xy_run_iter (const char *cmd,  unsigned long n,  void (*iter_func) (const char *
 static char *
 xy_run (const char *cmd, unsigned long n)
 {
-  xy_run_iter (cmd, n, NULL);
+  return xy_run_iter (cmd, n, NULL);
 }