package: openssl: Disable docs build

Building man pages requires pod2man tool. Avoid this extra build
dependency.

Signed-off-by: Phil Sutter <phil@nwl.cc>

package/openssl/Makefile

@@ -38,7 +38,7 @@ OPENSSL_OPTIONS:=	shared zlib-dynamic
 endif
 
 OPENSSL_OPTIONS+=	threads no-err no-tests no-fuzz-libfuzzer no-fuzz-afl 
-OPENSSL_OPTIONS+=	no-rc5 no-rc2 no-rc4 no-md2 no-idea
+OPENSSL_OPTIONS+=	no-rc5 no-rc2 no-rc4 no-md2 no-idea no-docs
 
 HOST_STYLE:=		manual
 CONFIG_STYLE:=		manual