When building with MINGW, specify `__USE_MINGW_ANSI_STDIO`.

This option is already present in the CMake config, but was missing from `Makefile.embed` and would cause all kinds of weird failures when compiling rugged on windows with the ruby devkit.

Makefile.embed

@@ -6,12 +6,12 @@ else
 	PREFIX=
 endif
 
-WIN32=0
+MINGW=0
 ifneq (,$(findstring MINGW32,$(PLATFORM)))
-	WIN32=1
+	MINGW=1
 endif
 ifneq (,$(findstring mingw,$(CROSS_COMPILE)))
-	WIN32=1
+	MINGW=1
 endif
 
 rm=rm -f
@@ -20,7 +20,7 @@ RANLIB=$(PREFIX)ranlib
 
 LIBNAME=libgit2.a
 
-ifeq ($(WIN32),1)
+ifeq ($(MINGW),1)
 	CC=gcc
 else
 	CC=cc
@@ -35,10 +35,10 @@ CFLAGS= -g $(DEFINES) -Wall -Wextra -O2 $(EXTRA_CFLAGS)
 
 SRCS = $(wildcard src/*.c) $(wildcard src/transports/*.c) $(wildcard src/xdiff/*.c) $(wildcard deps/http-parser/*.c) $(wildcard deps/zlib/*.c) src/hash/hash_generic.c
 
-ifeq ($(WIN32),1)
+ifeq ($(MINGW),1)
 	SRCS += $(wildcard src/win32/*.c) $(wildcard src/compat/*.c) deps/regex/regex.c
 	INCLUDES += -Ideps/regex
-	DEFINES += -DWIN32 -D_WIN32_WINNT=0x0501
+	DEFINES += -DWIN32 -D_WIN32_WINNT=0x0501 -D__USE_MINGW_ANSI_STDIO=1
 else
 	SRCS += $(wildcard src/unix/*.c) 
 	CFLAGS += -fPIC