I'm sorry, I'm not Colin, but you may look my config.log. I have same problem as Colin:
/usr/bin/ld: libssh2/openssl.o: undefined reference to symbol 'EVP_PKEY_free@@libcrypto.so.10'
/usr/bin/ld: note: 'EVP_PKEY_free@@libcrypto.so.10' is defined in DSO /usr/lib64/libcrypto.so so try adding it to the linker command line
/usr/lib64/libcrypto.so: could not read symbols: Invalid operation
collect2: error: ld returned 1 exit status
make[3]: *** [pgadmin3] Error 1