Add a test app that verifies PLACE_IN_SECTION, _SECTION_ATTR_SYMBOL_DECL_GENERIC,
_SECTION_START and _SECTION_END macros work correctly on Linux.
The test places 5 uint32_t values into a custom .test_data_table section from
two separate translation units, then iterates the section at runtime to verify
the correct count and content of all entries.
Includes:
- Custom linker script (ld/test_section.ld)
- Build-test-rules entry (linux only)
- pytest host_test marker
Add PLACE_IN_SECTION, _SECTION_ATTR_IMPL_GENERIC, _SECTION_ATTR_SYMBOL_DECL_GENERIC,
_SECTION_START and _SECTION_END macros that emit real section attributes on every
platform (embedded ELF, Linux ELF, macOS Mach-O).
Unlike _SECTION_ATTR_IMPL which is a no-op on Linux, these macros work uniformly
across all targets, enabling link-time arrays for error-code tables, init-function
arrays, and similar patterns.
Also moves _COUNTER_STRINGIFY definition before its first use.
Add Kconfig option SPIRAM_ALLOW_NOINIT_EXTERNAL_MEMORY
When enabled, a new linker script rule (from esp32.extram.noinit.ld)
places any variables in the .ext_ram.noinit section in SPIRAM.
This section is exempted from the startup SPIRAM memory test and is
not zero-initialized or added to the malloc pool, making it usable
for noinit variables that persist across reset.
The EXT_RAM_NOINIT_ATTR macro places variables in this section.
