Don't hardcode shared lib versions.

Index: src/common/cairo.cpp
--- src/common/cairo.cpp.orig
+++ src/common/cairo.cpp
@@ -331,7 +331,7 @@ wxCairo::wxCairo()
 #elif defined(__WXOSX__)
     wxString cairoDllStr("libcairo.2.dylib");
 #else
-    wxString cairoDllStr("libcairo.so.2");
+    wxString cairoDllStr("libcairo.so");
 #endif
     m_libCairo.Load(cairoDllStr);
     m_ok = m_libCairo.IsLoaded();
@@ -339,7 +339,7 @@ wxCairo::wxCairo()
         return;
 
 #if wxUSE_PANGO
-    m_libPangoCairo.Load("libpangocairo-1.0.so.0");
+    m_libPangoCairo.Load("libpangocairo-1.0.so");
     m_ok = m_libPangoCairo.IsLoaded();
     if ( !m_ok )
     {