restored actually needed g2c_* jpeg functions

src/dec_jpeg2000.c

@@ -141,6 +141,32 @@ int_dec_jpeg2000(char *injpc, g2int bufsize, void *outfld, int out_is_g2int)
     return 0;
 }
 
+/**
+ * This Function decodes a JPEG2000 code stream specified in the
+ * JPEG2000 Part-1 standard (i.e., ISO/IEC 15444-1) using [JasPer
+ * Software](https://github.com/jasper-software/jasper).
+ *
+ * @param injpc Pointer to buffer that holds the input JPEG2000 code
+ * stream.
+ * @param bufsize Length (in bytes) of the buffer that holds the input
+ * JPEG2000 code stream.
+ * @param outfld Pointer to int array, already allocated, that gets
+ * the unpacked data.
+ *
+ * @return
+ * - ::G2_JASPER_DECODE Error decode jpeg2000 code stream.
+ * - ::G2_JASPER_DECODE_COLOR decoded image had multiple color
+ *     components. Only grayscale is expected.
+ * - ::G2_JASPER_INIT Error inializing Jasper library.
+ *
+ * @author Ed Hartnett @date 9/7/22
+ */
+int
+g2c_dec_jpeg2000(char *injpc, size_t bufsize, int *outfld)
+{
+    return int_dec_jpeg2000(injpc, bufsize, outfld, 0);
+}
+
 /**
  * This Function decodes a JPEG2000 code stream specified in the
  * JPEG2000 Part-1 standard (i.e., ISO/IEC 15444-1) using [JasPer