Patch: Enable static builds

Hello,

We are building git statically in a container, however this require a tiny adjustment, and I would like to submit our patch, allowing others to painlessly do the same. The attached patch applies clean to master and v.2.53.0.

Changes included:

  *   Makefile: Add the STATIC_CURL_LIBS to targets where needed
  *   Shared.mak: Define STATIC_CURL_LIBS empty by default
  *   git-compat-util.h, usage.c: The symbol "error" is conflicting, so it is renamed in order to resolve this conflict.

Best regards,
Gergely