mingw: do load libcurl dynamically by default

This will help with Git for Windows' maintenance going forward: It
allows Git for Windows to switch its primary libcurl to a variant
without the OpenSSL backend, while still loading an alternate when
setting `http.sslBackend = openssl`.

This is necessary to avoid maintenance headaches with upgrading OpenSSL:
its major version name is encoded in the shared library's file name and
hence major version updates (temporarily) break libraries that are
linked against the OpenSSL library.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

Author: dscho

config.mak.uname

@@ -670,6 +670,7 @@ ifeq ($(uname_S),MINGW)
 	DEFAULT_HELP_FORMAT = html
 	HAVE_PLATFORM_PROCINFO = YesPlease
 	CSPRNG_METHOD = rtlgenrandom
+	LAZY_LOAD_LIBCURL = YesDoThatPlease
 	BASIC_LDFLAGS += -municode -Wl,--tsaware
 	COMPAT_CFLAGS += -DNOGDI -Icompat -Icompat/win32
 	COMPAT_CFLAGS += -DSTRIP_EXTENSION=\".exe\"