package/petitboot: propagate dependencies from kexec/kexec-lite

Commit 719921bebe17 (package/kexec: bump to version 2.0.27) forgot to
propagate the new dependency on kernel headers to petitboot, which may
select kexec, causing unmet dependencies warnings (unfortunately, not
errors), such as:

    $ KCONFIG_SEED=0x84462FFC make randconfig
    WARNING: unmet direct dependencies detected for BR2_PACKAGE_KEXEC
      Depends on [n]: BR2_PACKAGE_KEXEC_ARCH_SUPPORTS [=y] && BR2_TOOLCHAIN_HEADERS_AT_LEAST_3_17 [=n]
      Selected by [y]:
      - BR2_PACKAGE_PETITBOOT [=y] && (BR2_PACKAGE_KEXEC_ARCH_SUPPORTS [=y] || BR2_PACKAGE_KEXEC_LITE_ARCH_SUPPORTS [=n]) && BR2_USE_MMU [=y] && BR2_USE_WCHAR [=y] && !BR2_STATIC_LIBS [=n] && BR2_TOOLCHAIN_HAS_THREADS [=y] && BR2_PACKAGE_HAS_UDEV [=y] && !BR2_PACKAGE_KEXEC_LITE_ARCH_SUPPORTS [=n]

Propagate the dependency from kexec, and add comments about dependencies
also inherited from kexec-lite.

Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>
Cc: Laurent Vivier <laurent@vivier.eu>
Cc: Julien Olivain <ju.o@free.fr>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
(cherry picked from commit c721a583790ef9e35e2a974450bdcbc5662621c8)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/petitboot/Config.in

@@ -2,10 +2,11 @@ config BR2_PACKAGE_PETITBOOT
 	bool "petitboot"
 	depends on BR2_PACKAGE_KEXEC_ARCH_SUPPORTS || BR2_PACKAGE_KEXEC_LITE_ARCH_SUPPORTS
 	depends on BR2_USE_MMU # lvm2
-	depends on BR2_USE_WCHAR # elfutils
-	depends on !BR2_STATIC_LIBS # elfutils, lvm2
-	depends on BR2_TOOLCHAIN_HAS_THREADS # elfutils, lvm2
+	depends on BR2_USE_WCHAR # elfutils, kexec-lite
+	depends on !BR2_STATIC_LIBS # elfutils, kexec-lite, lvm2
+	depends on BR2_TOOLCHAIN_HAS_THREADS # elfutils, kexec-lite, lvm2
 	depends on BR2_PACKAGE_HAS_UDEV
+	depends on BR2_TOOLCHAIN_HEADERS_AT_LEAST_3_17 || !BR2_PACKAGE_KEXEC_ARCH_SUPPORTS # kexec
 	select BR2_PACKAGE_ELFUTILS
 	select BR2_PACKAGE_LVM2 # devmapper
 	select BR2_PACKAGE_NCURSES
@@ -36,3 +37,7 @@ comment "petitboot needs a toolchain w/ wchar, dynamic library, threads, udev /d
 	depends on !BR2_USE_WCHAR || BR2_STATIC_LIBS || \
 		!BR2_TOOLCHAIN_HAS_THREADS || \
 		!BR2_PACKAGE_HAS_UDEV
+
+comment "petitboot w/ kexec needs a toolchain w/ headers >= 3.17"
+	depends on BR2_PACKAGE_KEXEC_ARCH_SUPPORTS && !BR2_PACKAGE_KEXEC_LITE_ARCH_SUPPORTS
+	depends on !BR2_TOOLCHAIN_HEADERS_AT_LEAST_3_17