[PATCH] cmdline: configure input buffer size

[Gregory Etelson]

DPDK defines cmdline input buffer size to 512 characters.
That buffer size can be too small for long application input.
For example, the following flow template API testpmd command is 444
bytes long:
```
flow queue 0 create 0 template_table 1000 \
  pattern_template 0 actions_template 0 postpone no \
  pattern eth / ipv4 / udp / end \
  actions modify_field op set dst_type tag dst_level 0 dst_offset 0 \
    src_type value src_value 0x31 width 32 /  \
    modify_field op set dst_type ipv4_src src_type value \
    src_value 10101010 width 32 / modify_field op add dst_type \
    ipv4_ttl dst_level 0 dst_offset 0 src_type value \
    src_value ff width 8 / count / jump group 100 / end
```

The patch introduces conditional `RDLINE_CUSTOM_BUF_SIZE` definition.
Application can set custom cmdline size during DPDK configuration:

`meson setup ... -Dc_args='-DRDLINE_CUSTOM_BUF_SIZE=4096' ...`

Signed-off-by: Gregory Etelson <getelson at nvidia.com>
---
 lib/cmdline/cmdline_private.h | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/lib/cmdline/cmdline_private.h b/lib/cmdline/cmdline_private.h
index b64f363903..7908d963f9 100644
--- a/lib/cmdline/cmdline_private.h
+++ b/lib/cmdline/cmdline_private.h
@@ -17,7 +17,11 @@
 
 #include <cmdline.h>
 
+#ifndef RDLINE_CUSTOM_BUF_SIZE
 #define RDLINE_BUF_SIZE 512
+#else
+#define RDLINE_BUF_SIZE RDLINE_CUSTOM_BUF_SIZE
+#endif
 #define RDLINE_PROMPT_SIZE  32
 #define RDLINE_VT100_BUF_SIZE  8
 #define RDLINE_HISTORY_BUF_SIZE BUFSIZ
-- 
2.43.0