MSVC: link dynamically to the CRT

Dynamic linking is generally preferred over static linking, and MSVCRT.dll
has been integral part of Windows for a long time.

This also fixes linker warnings for _malloc and _free in zlib.lib, which
seems to be compiled for MSVCRT.dll already.

The DLL version also exports some of the CRT initialization functions,
which are hidden in the static libcmt.lib (e.g. __wgetmainargs, required by
subsequent Unicode patches).

Signed-off-by: Karsten Blees <blees@dcon.de>
Signed-off-by: Stepan Kasal <kasal@ucw.cz>
Acked-by: Sebastian Schuberth <sschuberth@gmail.com>
Acked-by: Marat Radchenko <marat@slonopotamus.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

config.mak.uname

@@ -358,16 +358,16 @@ ifeq ($(uname_S),Windows)
 		compat/win32/pthread.o compat/win32/syslog.o \
 		compat/win32/dirent.o
 	COMPAT_CFLAGS = -D__USE_MINGW_ACCESS -DNOGDI -DHAVE_STRING_H -DHAVE_ALLOCA_H -Icompat -Icompat/regex -Icompat/win32 -DSTRIP_EXTENSION=\".exe\"
-	BASIC_LDFLAGS = -IGNORE:4217 -IGNORE:4049 -NOLOGO -SUBSYSTEM:CONSOLE -NODEFAULTLIB:MSVCRT.lib
+	BASIC_LDFLAGS = -IGNORE:4217 -IGNORE:4049 -NOLOGO -SUBSYSTEM:CONSOLE
 	EXTLIBS = user32.lib advapi32.lib shell32.lib wininet.lib ws2_32.lib invalidcontinue.obj
 	PTHREAD_LIBS =
 	lib =
 ifndef DEBUG
-	BASIC_CFLAGS += -GL -Os -MT
+	BASIC_CFLAGS += -GL -Os -MD
 	BASIC_LDFLAGS += -LTCG
 	AR += -LTCG
 else
-	BASIC_CFLAGS += -Zi -MTd
+	BASIC_CFLAGS += -Zi -MDd
 endif
 	X = .exe
 endif