This changes Python API tests to use a single build shared across all
test functions, instead of the previous default behavior of a separate
build dir for each test function.
This build behavior opt-out, tests can use the previous behavior of one
individual (unshared) build directory per test function, by setting
`SHARED_BUILD_TESTCASE` to False (in the test class).
The motivation is to make the test suite more efficient, by not
repeatedly building the same test source. When running tests on my macOS
machine, this reduces the time of `ninja check-lldb-api` by almost 60%
(sample numbers: from ~492s down to ~207s = 58%). Almost 5min time
saved.
Each test function still calls `self.build()`, but only the first call
will do a build, in the subsequent tests `make` will be a no-op because
the sources won't have changed.
`INSERT BEFORE` keyword is not supported in current versions gold and
mold linkers. Since we cannot confirm accurately what linker and version
is available on the system and when it will be supported. We test it
with a sample program using the script keywords.
I think the only issue here was that we would erroneously consider
functions which are "in the middle" of the function were stepping to as
a part of the function, and would try to step into them (likely stepping
out of the function instead) instead of giving up early.
