Fix the problem when configure like following is done:
./configure CFLAGS='-I../libpcap -I.'
This gives:
CCOPT = -I../libpcap -I. -W -Wall [...]
See also the GitHub bug report #1313.
In Makefile.in, there is:
INCLS = -I. @V_INCLS@
Put $(INCLS) first in FULL_CFLAGS.
# Standard CFLAGS
CFLAGS = @CFLAGS@
-FULL_CFLAGS = $(CCOPT) $(DEFS) $(INCLS) $(CFLAGS)
+FULL_CFLAGS = $(INCLS) $(CCOPT) $(DEFS) $(CFLAGS)
# Standard LDFLAGS
LDFLAGS = @LDFLAGS@