Mine

gcc -DHAVE_CONFIG_H -I. -I. -I../.. -I../.. -I../../src -I../../src/sfutil  -I../../src/output-plugins -I../../src/detection-plugins -I../../src/dynamic-plugins -I../../src/preprocessors -I../../src/preprocessors/flow -I../../src/preprocessors/portscan  -I../../src/preprocessors/flow/int-snort  -I../../src/preprocessors/HttpInspect/include -I../../src/preprocessors/Stream5   -I/usr/local/include -I/usr/local/include/mysql -DENABLE_MYSQL -DENABLE_RESPONSE2 -I/usr/local/include  -g -O2 -Wall -DDYNAMIC_PLUGIN -DTIMESTATS -DPERF_PROFILING -c sp_respond2.c
In file included from sp_respond2.c:114:
../../src/decode.h:889: error: redefinition of `struct ip6_hdr'
*** Error code 1

Stop in /usr/local/src/snort-2.6.1.4/src/detection-plugins.
*** Error code 1

Stop in /usr/local/src/snort-2.6.1.4/src.
*** Error code 1

Stop in /usr/local/src/snort-2.6.1.4.
*** Error code 1

Stop in /usr/local/src/snort-2.6.1.4.