For Solaris data type uint64_t has to be defined.

--- gutenprint-5.3.3/src/cups/backend_common.h	2019-06-07 05:22:01.000000000 -0700
+++ gutenprint-5.3.3-mod/src/cups/backend_common.h	2020-10-20 22:30:38.761276448 -0700
@@ -42,6 +42,10 @@
 #ifndef __BACKEND_COMMON_H
 #define __BACKEND_COMMON_H
 
+#if defined (__SOLARIS__) || defined(__sun) 
+#define __uint64_t  uint64_t
+#endif 
+
 #define STR_LEN_MAX 64
 #define STATE( ... ) do { if (!quiet) fprintf(stderr, "STATE: " __VA_ARGS__ ); } while(0)
 #define ATTR( ... ) do { if (!quiet) fprintf(stderr, "ATTR: " __VA_ARGS__ ); } while(0)