Fix an issue with parentheses and separate values of union types

Since EDoc 0.7.7 (R14B02) separate values of union types can be
annotated. However, the parser has hitherto chosen not to add the
necessary parentheses due to backwards compatibility.

From this release on code traversing the output of edoc_parser needs
to take care of parentheses around separate values of union types.
Examples of such code are layout modules and doclet modules.

The following example shows annotated values of a union type:
-type t() :: (Name1 :: atom()) | (Name2 :: integer()).
Merge tag 'OTP_R15B02'

The R15B02 release
Merge branch 'maint'
[edoc] Introduce Unicode support for source files
Prepare OTP files for Unicode as default encoding
edoc: Remove support for packages
Implement ./otp_build configure --enable-silent-rules

With silent rules, the output of make is less verbose and compilation
warnings are easier to spot. Silent rules are disabled by default and
can be disabled or enabled at will by make V=0 and make V=1.
Merge branch 'nox/enable-silent-rules/OTP-10726'

* nox/enable-silent-rules/OTP-10726:
  Implement ./otp_build configure --enable-silent-rules
Prepare release
edoc: Fix building of documentation in sub directories

8115c0840527 broke building for projects that used sub directories
(but not packages).
Use ~ts for filenames
[edoc] Fix a bug involving a type declaration and a comment
Merge branch 'hb/edoc/bug_fix/OTP-10866'

* hb/edoc/bug_fix/OTP-10866:
  [edoc] Fix a bug involving a type declaration and a comment
Update copyright years
Prepare release