emacs-27 32c960b: Mention -lcurses problem on AIX

[Paul Eggert]

branch: emacs-27
commit 32c960bdc61e26521507f2d629ba4da8a4db842e
Author: Paul Eggert <eggert@cs.ucla.edu>
Commit: Paul Eggert <eggert@cs.ucla.edu>

    Mention -lcurses problem on AIX
    
    * etc/PROBLEMS: Describe problem with Emacs 27 and -lcurses.
    Do not merge to master.
---
 etc/PROBLEMS | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/etc/PROBLEMS b/etc/PROBLEMS
index 2ab76e5..7499726 100644
--- a/etc/PROBLEMS
+++ b/etc/PROBLEMS
@@ -2879,6 +2879,19 @@ A solution is to link with GCC, like this:
 Since the .o object files already exist, this will not recompile Emacs
 with GCC, but just restart by trying again to link temacs.
 
+*** Building Emacs with -lcurses fails with undefined symbols like BC.
+
+The 'configure' script attempts to use several terminal libraries,
+including tinfo, ncurses, and terminfo, and curses (in that order).
+If it happens to choose the long-obsolete curses library, Emacs will
+not link correctly.  Emacs 28 is expected to work around this problem;
+in the meantime you can work around it by installing tinfo, ncurses or
+terminfo instead.
+
+This problem can happen on AIX 7.2 if you build with IBM's compiler XLC,
+as AIX's ncurses library suffers from the libgcc problem mentioned above.
+To work around this, configure and build with GCC.
+
 *** Sun with acc: Link failure when using acc on a Sun.
 
 To use acc, you need additional options just before the libraries, such as