build: export correct function names

Detected by autobuild.sh, when targetting mingw.
Introduced in commit 98bfdff1.

* src/libvirt_private.syms: Fix typos.

src/libvirt_private.syms

@@ -274,8 +274,8 @@ virDomainGraphicsSpiceChannelModeTypeFromString;
 virDomainGraphicsSpiceChannelModeTypeToString;
 virDomainGraphicsSpiceChannelNameTypeFromString;
 virDomainGraphicsSpiceChannelNameTypeToString;
-virDomainGraphicsSpiceClipboardCopypasteFromString;
-virDomainGraphicsSpiceClipboardCopypasteToString;
+virDomainGraphicsSpiceClipboardCopypasteTypeFromString;
+virDomainGraphicsSpiceClipboardCopypasteTypeToString;
 virDomainGraphicsSpiceImageCompressionTypeFromString;
 virDomainGraphicsSpiceImageCompressionTypeToString;
 virDomainGraphicsSpiceJpegCompressionTypeFromString;