Fix distcheck due to custom iwMMXt rules
diff --git a/pixman/Makefile.am b/pixman/Makefile.am
index 1b232ad..deacf87 100644
--- a/pixman/Makefile.am
+++ b/pixman/Makefile.am
@@ -92,6 +92,7 @@
 
 # iwmmxt code
 if USE_ARM_IWMMXT
+libpixman_iwmmxt_la_SOURCES = pixman-mmx.c
 noinst_LTLIBRARIES += libpixman-iwmmxt.la
 libpixman_1_la_LIBADD += libpixman-iwmmxt.la