Fix missing declarration

Signed-off-by: Gabor Mezei <gabor.mezei@arm.com>
diff --git a/library/bignum_mod_raw.c b/library/bignum_mod_raw.c
index 6ac9e72..0d6810c 100644
--- a/library/bignum_mod_raw.c
+++ b/library/bignum_mod_raw.c
@@ -33,6 +33,8 @@
 #include "bignum_mod.h"
 #include "constant_time_internal.h"
 
+#include "bignum_mod_raw_invasive.h"
+
 void mbedtls_mpi_mod_raw_cond_assign(mbedtls_mpi_uint *X,
                                      const mbedtls_mpi_uint *A,
                                      const mbedtls_mpi_mod_modulus *N,