Fix: testsolv segfault

Fix: testsolv segfault

ERROR: AddressSanitizer: SEGV on unknown address 0x000000000000 (pc 0x7fab0e11bf2b bp 0x7ffdfc044b70 sp 0x7ffdfc044a90 T0)
0 0x7fab0e11bf2a in testcase_str2dep_complex /home/company/real_sanitize/libsolv-master/ext/testcase.c:577
1 0x7fab0e11c80f in testcase_str2dep /home/company/real_sanitize/libsolv-master/ext/testcase.c:656
2 0x7fab0e12e64a in testcase_read /home/company/real_sanitize/libsolv-master/ext/testcase.c:2952
3 0x402aa5 in main /home/company/real_sanitize/libsolv-master/tools/testsolv.c:148
4 0x7fab0d9d2a3f in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x20a3f)
5 0x401bb8 in _start (/home/company/real_sanitize/libsolv-master/build/install/bin/testsolv+0x401bb8)