regularize options which control size/speed trade

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

archival/Config.src

@@ -187,15 +187,17 @@ config FEATURE_GZIP_LONG_OPTIONS
 	help
 	  Enable use of long options, increases size by about 106 Bytes
 
-config GZIP_BIG_MEM
-       bool "Trade memory for gzip speed"
-       default n
-       depends on GZIP
-       help
-         Enable big memory options for gzip, including larger I/O
-         buffers and bigger hash tables.  Faster, but uses at least
-         twice as much memory.  Select if speed is more important than
-         memory use.
+config GZIP_FAST
+	int "Trade memory for gzip speed (0:small,slow - 2:fast,big)"
+	default 0
+	range 0 2
+	depends on GZIP
+	help
+	  Enable big memory options for gzip.
+	  0: small buffers, small hash-tables
+	  1: larger buffers, larger hash-tables
+	  2: larger buffers, largest hash-tables
+	  Larger models may give slightly better compression
 
 config LZOP
 	bool "lzop"
@@ -340,15 +342,12 @@ config UNLZMA
 	  is generally considerably better than that achieved by the bzip2
 	  compressors.
 
-	  The BusyBox unlzma applet is limited to de-compression only.
+	  The BusyBox unlzma applet is limited to decompression only.
 	  On an x86 system, this applet adds about 4K.
 
-	  Unless you have a specific application which requires unlzma, you
-	  should probably say N here.
-
 config FEATURE_LZMA_FAST
 	bool "Optimize unlzma for speed"
-	default y
+	default n
 	depends on UNLZMA
 	help
 	  This option reduces decompression time by about 25% at the cost of