package/rauc: select BR2_PACKAGE_LIBOPENSSL_ENGINES

This fixes link time errors, undefined references to various ENGINE_*
functions (paths shortened to the output directory):

host/lib/gcc/aarch64-buildroot-linux-musl/13.3.0/../../../../aarch64-buildroot-linux-musl/bin/ld: librauc.a.p/src_signature.c.o: in function `get_pkcs11_engine.constprop.0':
signature.c:(.text.get_pkcs11_engine.constprop.0+0x14): undefined reference to `ENGINE_load_builtin_engines'
host/lib/gcc/aarch64-buildroot-linux-musl/13.3.0/../../../../aarch64-buildroot-linux-musl/bin/ld: signature.c:(.text.get_pkcs11_engine.constprop.0+0x20): undefined reference to `ENGINE_by_id'
host/lib/gcc/aarch64-buildroot-linux-musl/13.3.0/../../../../aarch64-buildroot-linux-musl/bin/ld: signature.c:(.text.get_pkcs11_engine.constprop.0+0x54): undefined reference to `ENGINE_ctrl_cmd_string'
host/lib/gcc/aarch64-buildroot-linux-musl/13.3.0/../../../../aarch64-buildroot-linux-musl/bin/ld: signature.c:(.text.get_pkcs11_engine.constprop.0+0x60): undefined reference to `ENGINE_init'
host/lib/gcc/aarch64-buildroot-linux-musl/13.3.0/../../../../aarch64-buildroot-linux-musl/bin/ld: signature.c:(.text.get_pkcs11_engine.constprop.0+0xe0): undefined reference to `ENGINE_ctrl_cmd_string'
host/lib/gcc/aarch64-buildroot-linux-musl/13.3.0/../../../../aarch64-buildroot-linux-musl/bin/ld: signature.c:(.text.get_pkcs11_engine.constprop.0+0x128): undefined reference to `ENGINE_free'
host/lib/gcc/aarch64-buildroot-linux-musl/13.3.0/../../../../aarch64-buildroot-linux-musl/bin/ld: signature.c:(.text.get_pkcs11_engine.constprop.0+0x1a4): undefined reference to `ENGINE_finish'
host/lib/gcc/aarch64-buildroot-linux-musl/13.3.0/../../../../aarch64-buildroot-linux-musl/bin/ld: librauc.a.p/src_signature.c.o: in function `load_cert':
signature.c:(.text.load_cert+0x114): undefined reference to `ENGINE_ctrl_cmd'
host/lib/gcc/aarch64-buildroot-linux-musl/13.3.0/../../../../aarch64-buildroot-linux-musl/bin/ld: librauc.a.p/src_signature.c.o: in function `load_key':
signature.c:(.text.load_key+0x124): undefined reference to `ENGINE_load_private_key'

Before linking there were matching implicit declaration warnings
during compile.

[Peter: only select if libopenssl backend is used]
Signed-off-by: Fiona Klute <fiona.klute+wiwa@gmx.de>
Tested-by: Heiko Thiery <heiko.thiery@mail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/rauc/Config.in

@@ -5,6 +5,8 @@ config BR2_PACKAGE_RAUC
 	depends on BR2_USE_WCHAR # glib2
 	select BR2_PACKAGE_LIBGLIB2
 	select BR2_PACKAGE_OPENSSL
+	# uses ENGINE_* API
+	select BR2_PACKAGE_LIBOPENSSL_ENGINES if BR2_PACKAGE_LIBOPENSSL
 	select BR2_PACKAGE_SQUASHFS # run-time dependency
 	select BR2_PACKAGE_UBOOT_TOOLS if BR2_TARGET_UBOOT # run-time dependency
 	select BR2_PACKAGE_UBOOT_TOOLS_FWPRINTENV if BR2_TARGET_UBOOT