Changed every memcpy to SCA equivalent mbedtls_platform_memcpy

This makes physical attacks more difficult.
diff --git a/library/sha1.c b/library/sha1.c
index 842c11e..4032d11 100644
--- a/library/sha1.c
+++ b/library/sha1.c
@@ -328,7 +328,7 @@
 
     if( left && ilen >= fill )
     {
-        memcpy( (void *) (ctx->buffer + left), input, fill );
+        mbedtls_platform_memcpy( (void *) (ctx->buffer + left), input, fill );
 
         if( ( ret = mbedtls_internal_sha1_process( ctx, ctx->buffer ) ) != 0 )
             return( ret );
@@ -348,7 +348,7 @@
     }
 
     if( ilen > 0 )
-        memcpy( (void *) (ctx->buffer + left), input, ilen );
+        mbedtls_platform_memcpy( (void *) (ctx->buffer + left), input, ilen );
 
     return( 0 );
 }