Added GitHub Links to C issue reproduction programs

The idea behind that is to make sure, that even long after the issue will have been closed, we still can for academic interesst or other reasons go back and have a llook. These links are "permalinks".

c/test_programs/issue_175.c

@@ -5,6 +5,9 @@
 //
 // However, when compiled with "qvc issue_175.c" the program incorrectly outputs
 // x=989, v=96
+//
+// Details:
+// https://github.com/sy2002/QNICE-FPGA/issues/175
 
 #include <stdio.h>
 

c/test_programs/issue_177.c

@@ -1,6 +1,9 @@
 // This is a small test program to test Issue #177.
 // When compiled without optimization, it generates incorrect assembly.
 // When compiled with optimization, it generates correct assembly.
+//
+// Details:
+// https://github.com/sy2002/QNICE-FPGA/issues/177
 
 #include <sysdef.h>
 

c/test_programs/issue_75.c

@@ -9,6 +9,9 @@
    * qvc test.c -O1
    * qvc test.c -O2
    * qvc test.c -O3
+
+   Details:
+   https://github.com/sy2002/QNICE-FPGA/issues/75
 */
 
 #include <stdio.h>

c/test_programs/issue_76.c

@@ -3,6 +3,9 @@
    Expected result:  r=565, res=190
 
    Fixed. So the expected result should be shown.
+
+   Details:
+   https://github.com/sy2002/QNICE-FPGA/issues/76
 */
 
 #include <stdio.h>