Remove -Wno-attributes from -Wall tests.

It breaks compile time check for __attribute__((__symver__))
and it does not make sense either. Quoting gcc man page:

-Wno-attributes

Do not warn if an unexpected "__attribute__" is used, such as
unrecognized attributes, function attributes applied to variables,
etc. This does not stop errors for incorrect use of supported attributes.

Well, we do want to check for unsupported __attributes__ un our code,
right?

.gitlab/ci/clang-Wall

@@ -29,7 +29,6 @@ EXTRA="\
  -Wold-style-definition \
  -Wno-missing-field-initializers \
  -Wno-unused-parameter \
- -Wno-attributes \
  -Wno-long-long"
 
 exec $CLANG $PEDANTIC $CONVERSION \

.gitlab/ci/gcc-Wall

@@ -32,7 +32,6 @@ EXTRA="-Wextra \
  -Wold-style-definition \
  -Wno-missing-field-initializers \
  -Wno-unused-parameter \
- -Wno-attributes \
  -Wno-long-long \
  -Wmaybe-uninitialized \
  -Wvla"