unix: Disable FatFs VFS for normal build, keep enabled for coverage.

It's enabled mostly for unit testing, and we do that in full with coverage
build.

unix/Makefile

@@ -156,12 +156,11 @@ LIB_SRC_C = $(addprefix lib/,\
 	timeutils/timeutils.c \
 	)
 
-ifeq ($(MICROPY_FATFS),1)
+# FatFS VFS support
 LIB_SRC_C += $(addprefix lib/,\
 	fatfs/ff.c \
 	fatfs/option/ccsbcs.c \
 	)
-endif
 
 OBJ = $(PY_O)
 OBJ += $(addprefix $(BUILD)/, $(SRC_C:.c=.o))

unix/mpconfigport.h

@@ -130,8 +130,8 @@
 #define MICROPY_FATFS_VOLUMES          (3)
 #define MICROPY_FATFS_MAX_SS           (4096)
 #define MICROPY_FATFS_LFN_CODE_PAGE    (437) /* 1=SFN/ANSI 437=LFN/U.S.(OEM) */
-#define MICROPY_FSUSERMOUNT            (1)
+#define MICROPY_FSUSERMOUNT            (0)
-#define MICROPY_VFS_FAT                (1)
+#define MICROPY_VFS_FAT                (0)
 
 // Define to MICROPY_ERROR_REPORTING_DETAILED to get function, etc.
 // names in exception messages (may require more RAM).

unix/mpconfigport_coverage.h

@@ -31,3 +31,7 @@
 
 #define MICROPY_PY_URANDOM_EXTRA_FUNCS (1)
 #define MICROPY_PY_IO_BUFFEREDWRITER (1)
+#undef MICROPY_FSUSERMOUNT
+#undef MICROPY_VFS_FAT
+#define MICROPY_FSUSERMOUNT            (1)
+#define MICROPY_VFS_FAT                (1)