moved biggest stack buffers to malloc space, or made their size configurable

(8k of shell line edit buffer is an overkill)

# make ARCH=i386 bloatcheck
function                                             old     new   delta
read_line_input                                     3933    3967     +34
ifaddrlist                                           348     345      -3
do_loadfont                                          208     191     -17
edit_file                                            840     819     -21
.rodata                                           129112  129080     -32
uncompress                                          1305    1268     -37
loadfont_main                                        566     495     -71
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 1/6 up/down: 34/-181)          Total: -147 bytes

1 files changed, 11 insertions, 1 deletions

diff --git a/libbb/Config.in b/libbb/Config.in
index 112a3d658..a1ff7c056 100644
--- a/libbb/Config.in
+++ b/libbb/Config.in
@@ -30,7 +30,17 @@ config FEATURE_EDITING
         bool "Command line editing"
         default n
         help
-          Enable command editing (mainly for shell).
+          Enable line editing (mainly for shell command line).
+
+config FEATURE_EDITING_MAX_LEN
+        int "Maximum length of input"
+        range 128 8192
+        default 1024
+        depends on FEATURE_EDITING
+        help
+          Line editing code uses on-stack buffers for storage.
+          You may want to decrease this parameter if your target machine
+          benefits from smaller stack usage.
 
 config FEATURE_EDITING_FANCY_KEYS
         bool "Additional editing keys"