perf: fix build with musl on PowerPC

Signed-off-by: Matthias Schiffer <mschiffer@universe-factory.net>

package/devel/perf/musl-include/asm/errno.h

+#ifndef __MUSL_COMPAT_ASM_ERRNO_H
+#define __MUSL_COMPAT_ASM_ERRNO_H
+
+/* Avoid including different versions of errno.h, the defines (incorrectly)
+ * cause a redefinition error on PowerPC */
+#include <errno.h>
+
+#endif