build: add -Wshadow to the dev build

[pacovn]

Summary

Add the '-Wshadow' to the dev build (discussed with @donaldsharp after PR's #3006, #3007, #3009)

Components

build

[LabN-CI]

💚 Basic BGPD CI results: SUCCESS, 0 tests failed

Results table

_	_
Result	SUCCESS git merge/3017 2029a0f
Date	09/13/2018
Start	11:10:11
Finish	11:33:15
Run-Time	23:04
Total	1816
Pass	1816
Fail	0
Valgrind-Errors	0
Valgrind-Loss	0
Details	vncregress-2018-09-13-11:10:11.txt
Log	autoscript-2018-09-13-11:10:48.log.bz2

For details, please contact louberger

[NetDEF-CI]

Continuous Integration Result: SUCCESSFUL

Congratulations, this patch passed basic tests

Tested-by: NetDEF / OpenSourceRouting.org CI System

CI System Testrun URL: https://ci1.netdef.org/browse/FRR-FRRPULLREQ-5295/

This is a comment from an EXPERIMENTAL automated CI system.
For questions and feedback in regards to this CI system, please feel free to email
Martin Winter - mwinter (at) opensourcerouting.org.

---

CLANG Static Analyzer Summary

• Github Pull Request 3017, comparing to Git base SHA 6efca34
• Base image data for Git 6efca34 does not exist - compare skipped

[eqvinox]

wrong place (refer to inline comment)

[eqvinox]

Wrong place to add this; please put it a few lines down, below
dnl always want these CFLAGS

BTW, the difference between

AC_C_FLAG([-Wwrite-strings]) <--- HERE(A)
if test x"${enable_gcc_ultra_verbose}" = x"yes" ; then
  AC_C_FLAG([-Wcast-qual])   <--- HERE(B)

is that the warnings in place (A) should always be clean in CI (and CI fails if there is a new warning), while the warnings under (B) are "informative" and we don't want CI to be strict about them.

[pacovn]

Thank you! :-)

[NetDEF-CI]

Continuous Integration Result: SUCCESSFUL

Congratulations, this patch passed basic tests

Tested-by: NetDEF / OpenSourceRouting.org CI System

CI System Testrun URL: https://ci1.netdef.org/browse/FRR-FRRPULLREQ-5329/

This is a comment from an EXPERIMENTAL automated CI system.
For questions and feedback in regards to this CI system, please feel free to email
Martin Winter - mwinter (at) opensourcerouting.org.

---

CLANG Static Analyzer Summary

• Github Pull Request 3017, comparing to Git base SHA b4657ea

No Changes in Static Analysis warnings compared to base

[LabN-CI]

💚 Basic BGPD CI results: SUCCESS, 0 tests failed

Results table

_	_
Result	SUCCESS git merge/3017 2b5773b
Date	09/17/2018
Start	13:20:11
Finish	13:43:18
Run-Time	23:07
Total	1816
Pass	1816
Fail	0
Valgrind-Errors	0
Valgrind-Loss	0
Details	vncregress-2018-09-17-13:20:11.txt
Log	autoscript-2018-09-17-13:20:49.log.bz2

For details, please contact louberger

[pacovn]

@eqvinox Hi, I've updated the commit with your request :-)