openssl: disable ccache usage

ccache and openssl don't get on:

| make[1]: Entering directory '/home/prj/yocto/build/tmp/work/core2-64-poky-linux/openssl/1.0.2o-r0/openssl-1.0.2o/crypto' | ccache: invalid option -- 'D'

Disable the use of ccache in the openssl recipe until someone root-causes this.

[ YOCTO #12810 ]

---
 meta/recipes-connectivity/openssl/openssl10.inc | 3 +++
 1 file changed, 3 insertions(+)

index f7a8de823a5..995177d3209 100644
@@ -33,6 +33,9 @@ export DIRS = "crypto ssl apps"
 export EX_LIBS = "-lgcc -ldl"
 export AS = "${CC} -c"
 
+# openssl fails with ccache: https://bugzilla.yoctoproject.org/show_bug.cgi?id=12810
+CCACHE = ""
+
 inherit pkgconfig siteinfo multilib_header ptest relative_symlinks
 
 PACKAGES =+ "libcrypto libssl ${PN}-misc openssl-conf"

2.11.0