Fix v7/v8-compatible build

Broken by 3ab68cf563f6edc2608c085f5c8b2d5d5c61157e

Fixes #60

jdapistd.c

diff --git a/jdapistd.c b/jdapistd.c
index 06076cb..37afc84 100644
--- a/jdapistd.c
+++ b/jdapistd.c
@@ -190,7 +190,7 @@
    * single-pass decompression case, allowing us to use the same MCU column
    * width for all of the components.
    */
-  align = cinfo->min_DCT_scaled_size * cinfo->max_h_samp_factor;
+  align = cinfo->_min_DCT_scaled_size * cinfo->max_h_samp_factor;
 
   /* Adjust xoffset to the nearest iMCU boundary <= the requested value */
   input_xoffset = *xoffset;