make the thing compile, remove drmingw stuff from 64bit builds

and properly link libbacktrace

rip in piece drmingw but we got goddamn 64bit crashlogs now c:

libs/DLL-README.txt

@@ -27,7 +27,4 @@ and don't forget to build r_opengl.dll for srb2dd.
 * libs\dll-binaries\x86_64\discord-rpc.dll
 * libs\SDL2\x86_64-w64-mingw32\bin\SDL2.dll
 * libs\SDL2_mixer\x86_64-w64-mingw32\bin\*.dll (get everything)
-* libs\libopenmpt\x86_64\bin\mingw\libopenmpt.dll
-* libs\libbacktrace\bin\x86_64\libbacktrace-0.dll
-* libs\libbacktrace\bin\x86_64\libgcc_s_seh-1.dll
-* libs\libbacktrace\bin\x86_64\libwinpthread-1.dll
+* libs\libopenmpt\x86_64\bin\mingw\libopenmpt.dll

src/sdl/Makefile.cfg

@@ -108,6 +108,10 @@ endif
 
 ifndef NOLIBBACKTRACE
 	OPTS+=-DHAVE_LIBBACKTRACE
+ifdef MINGW64
+	CPPFLAGS+=-I../libs/libbacktrace/include
+	LDFLAGS+=-L../libs/libbacktrace/lib/x86_64
+endif
 	LIBS:=-lbacktrace $(LIBS)
 endif
 

src/win32/Makefile.cfg

@@ -63,11 +63,7 @@ else
 endif
 endif
 
-ifdef MINGW64
-	CPPFLAGS+=-I../libs/drmingw/include
-	LDFLAGS+=-L../libs/drmingw/lib/win64
-	LIBS+=-lmgwhelp -lexchndl
-else
+ifndef MINGW64
 	CPPFLAGS+=-I../libs/drmingw/include
 	LDFLAGS+=-L../libs/drmingw/lib/win32
 	LIBS+=-lmgwhelp -lexchndl