[ptxdist] Build U-Boot against host-openssl fails

[Alexander Dahl <ada@thorsis.com>]

Hei hei,

although claiming it's optional latest U-Boot versions require OpenSSL on the 
host.¹  I added an option to build host-openssl with commit 
0c779a60e50c40d522b1e9c20b5c75b2e57fde5a ("u-boot: Add option to depend on 
host-openssl") but ptxdist u-boot package still fails to link to host openssl 
package, message is always missing some openssl symbols.

I tried the same thing as barebox now in rules/u-boot.make like this:

+# use host pkg-config for host tools
+U_BOOT_PATH        := PATH=$(HOST_PATH)

This does not help. 

I'm somehow suspecting the wrong pkg-config is called.  Affected is not the 
target image, but the host tools (like mkimage) built alongside with the 
target stuff (which you 1) can not disable to build and 2) need for certain 
parts of the ptxdist package anyways, so not building those is no option).

I tried each combination of PTXCONF_U_BOOT_NEEDS_HOST_OPENSSL and 
CONFIG_TOOLS_LIBCRYPTO in U-Boot kconfig, all fail.

buildroot has a fix for building against host-openssl, but I don't understand 
it, and I'm not sure if the same approach would work in ptxdist.

Any ideas?

(Disclaimer: this only happens on a quite recent U-Boot, e.g. from 2022.)
(More disclaimer: it does not happen if libssl-dev is installed on the build 
host.)

Greets
Alex

¹ I consider this a bug, and I'm not the only one, but several attempts to fix 
this in upstream U-Boot did not lead to merge any fix.