libressl: provide fake openssl pkgconfig files
libressl: fix issue with programs using -fvisibility=hidden

they use the address of main as a bogus way to generate entropy.
this breaks anything that uses -fvisibility=hidden.
for example

gcc test.c -lcurl -fvisibility=hidden
/bin/ld: a.out: hidden symbol `main' in /tmp/ccobhDjc.o is referenced by DSO

readelf -a /lib/libcrypto.so | grep main
000000345708  000a00000006 R_X86_64_GLOB_DAT 0000000000000000 main + 0
     10: 0000000000000000     0 NOTYPE  GLOBAL DEFAULT  UND main
   2146: 0000000000000000     0 NOTYPE  GLOBAL DEFAULT  UND main
libressl: remove unrecognized configure flags