Fixed FTBFS caused by switch to ruby2.0. This resolves bug 2031.

amarok/configure.in.in

@@ -1125,6 +1125,12 @@ if test -n "$PKG_CONFIG"; then
       RUBY_CFLAGS=`$PKG_CONFIG ruby-1.9 --cflags`
     fi
   fi
+  if test -z "$RUBY_VERSION"; then
+    RUBY_VERSION=`$PKG_CONFIG ruby-2.0 --modversion 2>/dev/null`
+    if test -n "$RUBY_VERSION"; then
+      RUBY_CFLAGS=`$PKG_CONFIG ruby-2.0 --cflags`
+    fi
+  fi
   if test -z "$RUBY_VERSION"; then
     # pkgconfig file does not exist but might be 1.9.1: RUBY_VERSION defined in ruby/version.h
     if test -n "$RUBY -r rbconfig -e 'printf("%s",RbConfig::CONFIG@<:@"rubyhdrdir"@:>@)'"; then