Configure.ac: cleanup

Removal of tabs and trailing spaces
Fixing configuration with autoconf 2.67

configure.ac

@@ -2164,7 +2164,10 @@ AS_IF([test "${enable_gme}" != "no"], [
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 dnl  SIDPlay plugin
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-PKG_WITH_MODULES([SID], [libsidplay2],
+AC_ARG_ENABLE(sid,
+    [AS_HELP_STRING([--enable-sid],[C64 sid demux support (default auto)])])
+AS_IF([test "${enable_sid}" != "no"], [
+    PKG_CHECK_MODULES(sid, [libsidplay2], [
         AC_LANG_PUSH(C++)
         oldCPPFLAGS="$CPPFLAGS"
         CPPFLAGS="$CPPFLAGS $SID_CFLAGS"
@@ -2179,12 +2182,14 @@ PKG_WITH_MODULES([SID], [libsidplay2],
                 )
         ])
         CPPFLAGS="$oldCPPFLAGS"
-		AC_LANG_POP(C++),
+        AC_LANG_POP(C++)
+    ], [
         AS_IF([test "x${enable_sid}" = "xyes"],
             [AC_MSG_ERROR(Library libsidplay2 needed for sid was not found)],
             [AC_MSG_WARN(Library libsidplay2 needed for sid was not found)]
-			),
-		[C64 sid demux support], [auto])
+            )
+    ])
+])
 
 
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