[sysvabi64] Require PT_GNU_PROPERTY when program properties used.

Added a requirement that a static linker must generate a
PT_GNU_PROPERTY program header for an executable or shared-library
that contains program properties.

The linux kernel and glibc are currently relying on the program
header to find the program properties and are not attempting to
search through the consolidated notes section (PT_NOTE) program
header if it isn't present.

fixes: #299

sysvabi64/sysvabi64.rst

@@ -210,6 +210,10 @@ Change History
  |            |                              |   used by `PAuthABIELF64`_ and                        |
  |            |                              |   `MemTagABIELF64`_.                                  |
  +------------+------------------------------+-------------------------------------------------------+
+ | 2024Q4     | 29\ :sup:`th` November 2024  | Require that ``PT_GNU_PROPERTY`` program header be    |
+ |            |                              | present in executables and shared-libraries if a      |
+ |            |                              | .note.gnu.property section is present.                |
+ +------------+------------------------------+-------------------------------------------------------+
 
 References
 ----------
@@ -1670,6 +1674,17 @@ include:
 * Any functions used by the program that manipulate the stack such as
   ``setjmp`` and ``longjmp``, must be aware of GCS.
 
+Program Properties and program headers
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+An executable or shared-library containing Program Properties must
+have a ``PT_GNU_PROPERTY`` program header [LINUX_ABI_] to identify
+the location of the program properties to the program loader.
+
+The program header must be generated even if the
+``.note.gnu.property`` is consolidated into another section of type
+SHT_NOTE.
+
 Tool Requirements for generating BTI instructions
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
@@ -1735,6 +1750,13 @@ calls to that location.
 Program Loading
 ---------------
 
+Locating GNU properties
+^^^^^^^^^^^^^^^^^^^^^^^
+
+A program loader may rely on the presence of a ``PT_GNU_PROPERTY``
+program header to locate the ``.note.gnu.property`` section in an
+executable or shared-object.
+
 Process ``GNU_PROPERTY_AARCH64_FEATURE_1_BTI``
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^