[val] Add extra context to error messages.
This CL extends the error messages produced by the validator to output the
disassembly of the errored line.
The validation_id messages have also been updated to print the line number of
the error instead of the word number. Note, the error number is from the start
of the SPIR-V, it does not include any headers printed in the disassembled code.
Fixes#670, #1581
Add pkg-config file for shared libraries
Properly build SPIRV-Tools DLL
Test C interface with shared library
Set PATH to shared library file for c_interface_shared test
Otherwise, the test won't find SPIRV-Tools-shared.dll.
Do not use private functions when testing with shared library
Make all symbols hidden by default for shared library target
According to the SPIRV Spec (2.16.1):
* There is at least one OpEntryPoint instruction, unless the Linkage
capability is being used.
* No function can be targeted by both an OpEntryPoint instruction and an
OpFunctionCall instruction.
Also updated unit tests to includ OpEntryPoint.
