Bug#808628: apron: FTBFS: ap_config.h: error: expected identifier or ‘(’ before ‘__extension__’

["Chris West (Faux)" <solo-debianbugs@goeswhere.com>]

Source: apron
Version: 0.9.10-6
Severity: serious
Justification: fails to build from source
Tags: sid 
User: reproducible-builds@lists.alioth.debian.org
Usertags: ftbfs
X-Debbugs-CC: reproducible-builds@lists.alioth.debian.org

Dear Maintainer,

The package fails to build:

make[4]: Entering directory '/apron-0.9.10/apron/itv'
gcc -Wcast-qual -Wswitch -Werror-implicit-function-declaration -Wall -Wextra -Wundef -Wbad-function-cast -Wcast-align -Wstrict-prototypes -Wno-unused -std=c99 -U__STRICT_ANSI__ -fPIC -O3 -DNDEBUG -I../num -I../apron -I/usr/include -I/usr/include -DNUM_MPQ -c -o itvMPQ.o itv.c
In file included from /usr/include/string.h:634:0,
                 from ../num/num.h:11,
                 from itv.h:9,
                 from itv.c:5:
../apron/ap_config.h:28:21: error: expected identifier or ‘(’ before ‘__extension__’
 static inline char* strdup(const char* s){
                     ^
Makefile:146: recipe for target 'itvMPQ.o' failed
make[4]: *** [itvMPQ.o] Error 1
make[4]: Leaving directory '/apron-0.9.10/apron/itv'
Makefile:19: recipe for target 'c' failed
make[3]: *** [c] Error 2

Full build log:
https://reproducible.debian.net/rb-pkg/unstable/amd64/apron.html

-- System Information:
Debian Release: stretch/sid
APT prefers unstable
APT policy: (500, 'unstable')
Architecture: amd64 (x86_64)