efivar: upgrade 38 -> 39

Changelog:
==========
-Add -T workaround for GNU ld 2.36
-Add extern "C" to headers for easier use by C++
-Avoid format error on i686
-Fix the -march issue for riscv64
-Fix musl build
-Fix invalid free in main()
-Remove deprecated --add-needed linker flag
-src/Makefile: build util.c separately for makeguids
-Adjust dependency for libefivar and libefiboot objects
-Set LC_ALL=C to force English output from ld
-LLD: fix detection and remove not needed workarounds
-Fix glibc 2.36 build (mount.h conflicts)
-File device paths: don't print "File(" or ")"
-Use off_t instead of off64_t
-Revamp efi_well_known_* variable handling
-Allow overriding PKG_CONFIG
-Allow passing of hex values to -A
-Allow -a to create a non-existent variable
-make: add option to disable building/installing the docs
-esl-iter.h: fix type declaration of return value for gcc-13
-Minor code updates
-src/Makefile: do not override LIBS and CFLAGS for prerequisites
-linux: handle non-ACPI systems in device_get()
-Change set&append data to be const.
-dp.h: check _ucs2size in format_ucs2()
-Fix wrong if condition in efi_variable_get_data
-Make README statement match license
-Remove needless access() in efivarfs_probe()

(From OE-Core rev: d8fdd64d13d5598b16ddf7329d5ca283ec7da518)

Signed-off-by: Wang Mingyu <wangmy@fujitsu.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-bsp/efivar/efivar_39.bb

@@ -10,7 +10,7 @@ COMPATIBLE_HOST = "(i.86|x86_64|arm|aarch64).*-linux"
 SRC_URI = "git://github.com/rhinstaller/efivar.git;branch=main;protocol=https \
            file://0001-docs-do-not-build-efisecdb-manpage.patch \
            "
-SRCREV = "90e88b221e8bc60dc50f3246051369b8f580c0d0"
+SRCREV = "c47820c37ac26286559ec004de07d48d05f3308c"
 PV .= "+39+git"
 
 S = "${WORKDIR}/git"