pickcdef: mark read-only array as const

Change-Id: If1c306b742f56a19bcd720c555ba30ab8f0b8a1b
diff --git a/av1/encoder/pickcdef.c b/av1/encoder/pickcdef.c
index 969684a..ecadb0d 100644
--- a/av1/encoder/pickcdef.c
+++ b/av1/encoder/pickcdef.c
@@ -25,7 +25,7 @@
 #define REDUCED_TOTAL_STRENGTHS (REDUCED_PRI_STRENGTHS * CDEF_SEC_STRENGTHS)
 #define TOTAL_STRENGTHS (CDEF_PRI_STRENGTHS * CDEF_SEC_STRENGTHS)
 
-static int priconv[REDUCED_PRI_STRENGTHS] = { 0, 1, 2, 3, 5, 7, 10, 13 };
+static const int priconv[REDUCED_PRI_STRENGTHS] = { 0, 1, 2, 3, 5, 7, 10, 13 };
 
 /* Search for the best strength to add as an option, knowing we
    already selected nb_strengths options. */