Support 8-bit & 12-bit JPEGs using the same build

Partially implements #199

This commit also implements a request from #178 (the ability to compile
the libjpeg example as a standalone program.)

jconfig.h.in

@@ -9,29 +9,39 @@
 /* libjpeg-turbo version in integer form */
 #define LIBJPEG_TURBO_VERSION_NUMBER  @LIBJPEG_TURBO_VERSION_NUMBER@
 
-/* Support arithmetic encoding */
+/* Support arithmetic encoding when using 8-bit samples */
 #cmakedefine C_ARITH_CODING_SUPPORTED 1
 
-/* Support arithmetic decoding */
+/* Support arithmetic decoding when using 8-bit samples */
 #cmakedefine D_ARITH_CODING_SUPPORTED 1
 
 /* Support in-memory source/destination managers */
 #cmakedefine MEM_SRCDST_SUPPORTED 1
 
-/* Use accelerated SIMD routines. */
+/* Use accelerated SIMD routines when using 8-bit samples */
 #cmakedefine WITH_SIMD 1
 
-/*
- * Define BITS_IN_JSAMPLE as either
- *   8   for 8-bit sample values (the usual setting)
- *   12  for 12-bit sample values
- * Only 8 and 12 are legal data precisions for lossy JPEG according to the
- * JPEG standard, and the IJG code does not support anything else!
- * We do not support run-time selection of data precision, sorry.
- */
+#ifdef _WIN32
 
-#define BITS_IN_JSAMPLE  @BITS_IN_JSAMPLE@      /* use 8 or 12 */
+#undef RIGHT_SHIFT_IS_UNSIGNED
+
+/* Define "boolean" as unsigned char, not int, per Windows custom */
+#ifndef __RPCNDR_H__            /* don't conflict if rpcndr.h already read */
+typedef unsigned char boolean;
+#endif
+#define HAVE_BOOLEAN            /* prevent jmorecfg.h from redefining it */
+
+/* Define "INT32" as int, not long, per Windows custom */
+#if !(defined(_BASETSD_H_) || defined(_BASETSD_H))   /* don't conflict if basetsd.h already read */
+typedef short INT16;
+typedef signed int INT32;
+#endif
+#define XMD_H                   /* prevent jmorecfg.h from redefining it */
+
+#else
 
 /* Define if your (broken) compiler shifts signed values as if they were
    unsigned. */
 #cmakedefine RIGHT_SHIFT_IS_UNSIGNED 1
+
+#endif