[source] kernel: fix build error in sign-file.c with libressl

[LEDE Commits]

nbd pushed a commit to source.git, branch master:
https://git.lede-project.org/2b3b63aea301412b2c42e7bfe3c59e566ac4eaa9

commit 2b3b63aea301412b2c42e7bfe3c59e566ac4eaa9
Author: Felix Fietkau <nbd at nbd.name>
AuthorDate: Thu Sep 29 11:23:27 2016 +0200

    kernel: fix build error in sign-file.c with libressl
    
    Signed-off-by: Felix Fietkau <nbd at nbd.name>
---
 .../generic/patches-4.4/211-sign-file-libressl.patch     | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/target/linux/generic/patches-4.4/211-sign-file-libressl.patch b/target/linux/generic/patches-4.4/211-sign-file-libressl.patch
new file mode 100644
index 0000000..c174087
--- /dev/null
+++ b/target/linux/generic/patches-4.4/211-sign-file-libressl.patch
@@ -0,0 +1,16 @@
+LibreSSL disables the CMS subsystem, so sign-file.c needs to fall back to using
+PKCS#7 in that case.
+
+Signed-off-by: Felix Fietkau <nbd at nbd.name>
+
+--- a/scripts/sign-file.c
++++ b/scripts/sign-file.c
+@@ -39,7 +39,7 @@
+  * signing with anything other than SHA1 - so we're stuck with that if such is
+  * the case.
+  */
+-#if OPENSSL_VERSION_NUMBER < 0x10000000L
++#if defined(LIBRESSL_VERSION_NUMBER) || OPENSSL_VERSION_NUMBER < 0x10000000L
+ #define USE_PKCS7
+ #endif
+ #ifndef USE_PKCS7