cmTarget: Drop internal cache of link interface usage requirements

These use a huge amount of memory that accumulates as generation
proceeds.  On the Unix Makefiles generator, only GetIncludeDirectories
and GetCompileDefinitions are even called more than once per target
(once for build files, once for dependency scanning preprocessor info).
Another approach will be needed to avoid duplicate computation in the
cases where it does occur.
cmTarget: Drop internal cache of build properties

These use a huge amount of memory that accumulates as generation
proceeds.  On the Unix Makefiles generator, only GetIncludeDirectories
and GetCompileDefinitions are even called more than once per target
(once for build files, once for dependency scanning preprocessor info).
Another approach will be needed to avoid duplicate computation in the
cases where it does occur.
genex-head-sensitive-conditions
Merge topic 'target-drop-build-setting-cache' into next

c3de083e genex-head-sensitive-conditions
e5821c20 cmTarget: Drop internal cache of build properties
bbea91c7 cmTarget: Drop internal cache of link interface usage requirements
Revert topic 'target-drop-build-setting-cache'

It contained changes not ready for testing.
Merge topic 'target-drop-build-setting-cache' into next

b154a32d Revert topic 'target-drop-build-setting-cache'
cmTarget: Drop internal cache of link interface usage requirements

These use a huge amount of memory that accumulates as generation
proceeds.  On the Unix Makefiles generator, only GetIncludeDirectories
and GetCompileDefinitions are even called more than once per target
(once for build files, once for dependency scanning preprocessor info).
Another approach will be needed to avoid duplicate computation in the
cases where it does occur.
cmTarget: Drop internal cache of build properties

These use a huge amount of memory that accumulates as generation
proceeds.  On the Unix Makefiles generator, only GetIncludeDirectories
and GetCompileDefinitions are even called more than once per target
(once for build files, once for dependency scanning preprocessor info).
Another approach will be needed to avoid duplicate computation in the
cases where it does occur.
Merge topic 'target-drop-build-setting-cache' into next

133cd996 cmTarget: Drop internal cache of build properties
a4d58722 cmTarget: Drop internal cache of link interface usage requirements