screenshot: Defining the public API

Add public API for taking screenshots of current domain console.

* include/libvirt/libvirt.h.in: add virDomainScreenshot
* src/libvirt_public.syms: Export new symbol

include/libvirt/libvirt.h.in

@@ -669,6 +669,14 @@ int                     virDomainCoreDump       (virDomainPtr domain,
                                                  const char *to,
                                                  int flags);
 
+/*
+ * Screenshot of current domain console
+ */
+char *                  virDomainScreenshot     (virDomainPtr domain,
+                                                 virStreamPtr stream,
+                                                 unsigned int screen,
+                                                 unsigned int flags);
+
 /*
  * Domain runtime information
  */

src/libvirt_public.syms

@@ -439,6 +439,7 @@ LIBVIRT_0.9.0 {
 LIBVIRT_0.9.2 {
     global:
         virDomainInjectNMI;
+        virDomainScreenshot;
 } LIBVIRT_0.9.0;
 
 # .... define new API here using predicted next version number ....