Bison's test 464 (Syntax error as exception) fails on the CI.
Do not use clang with asan on Ubuntu's libc++.
https://bugs.llvm.org/show_bug.cgi?id=17379
* .travis.yml (Clang 7 libc++ and ASAN): New.
(Clang 6 -O3 and libc++): Really use libc++.
(Clang 5): Don't use libc++, nor asan (does not work either, same
reason).
* .travis.yml: Don't define CC/CXX, it does not work.
Use `[[...]]` instead of `[...]`.
Show the compiler versions.
(Clang 3.3, Clang 3.4): Specify the path to avoid using
/usr/local/clang-5.0.0/bin's clang.
Putting them in the env is useless. We don't want to pass
`CPPFLAGS="$CPPFLAGS"` to configure, as it means "set it to nothing"
when $CPPFLAGS is not set, which is not what we want.
This correctly started to use libc++, but it is not installed on the
Ubuntu. We will see later if we can use it.
* .travis.yml: Define CONFIGUREFLAGS, and pass it to configure.
* build-aux/install-icc.sh: New.
* .travis.yml (icc): New.
Use -k to get as many errors as possible from the start.
* src/complain.c (warnings_types): Use a more precise type.
For some reasons, the checkout on travis may not have any tags, so
`git describe` fails, so bootstrap fails.
* .travis.yml: If git describe fails, install some tag.
We have failures on Flex output, which are probably related to an old
release. Let's check.
In file included from src/scan-code-c.c:3:
src/scan-code.c:2198:21: error: empty paragraph passed to '@param' command
[-Werror,-Wdocumentation]
* @param line_number
~~~~~~~~~~~~~~~~~^
* .travis.yml: here.
Running all these tests might be overkill: it is very long, and don't
need full portability checks. Besides, some tests under Valgrind are
too slow and get killed by the CI (timeout of 10min without output).
* .travis.yml: here.
