Change type of ldc.dso_initialized to i8.

Also being only a flag, it is safer to use the i8 type and compare against 0.
This adds only an icmp instruction to the IR and should not change the generated machine code.
Fix a typo in variable name
Merge pull request #685 from redstar/dso

Change type of ldc.dso_initialized to i8.
Always link in libcurl when building dmd-testsuite.
Merge testsuite workaround for LLVM issue 20292.