AIX: Add an option to disable automatic exports from shared libraries

Since commit 0f150b69d3 (AIX: Explicitly compute shared object exports
for both XL and GNU, 2019-07-11, v3.16.0-rc1~418^2~2) we always export
all symbols from shared libraries by default.  Add a new target property
called `AIX_EXPORT_ALL_SYMBOLS` that can be explicitly set to OFF to
suppress this behavior and export no symbols by default.

Fixes: #20290

1 files changed, 5 insertions, 0 deletions

diff --git a/Source/cmRulePlaceholderExpander.cxx b/Source/cmRulePlaceholderExpander.cxx
index 0a1d109..5ab1b3a 100644
--- a/Source/cmRulePlaceholderExpander.cxx
+++ b/Source/cmRulePlaceholderExpander.cxx
@@ -85,6 +85,11 @@ std::string cmRulePlaceholderExpander::ExpandRuleVariable(
       return replaceValues.ObjectsQuoted;
     }
   }
+  if (replaceValues.AIXExports) {
+    if (variable == "AIX_EXPORTS") {
+      return replaceValues.AIXExports;
+    }
+  }
   if (replaceValues.Defines && variable == "DEFINES") {
     return replaceValues.Defines;
   }