Fix buildsystem to explicitly compile with -std=gnu89 to avoid
differencs in inline semantics introduced in GCC5.
https://bugs.gentoo.org/show_bug.cgi?id=570598

Additionally, fix QA issues caused by implicit declarations, such as:
* QA Notice: Package triggers severe warnings which indicate that it
*            may exhibit random runtime failures.
* pork_inet.c:69:8: warning: implicit declaration of function ‘vasprintf’ [-Wimplicit-function-declaration]

--- pork-0.99.8.1/configure.ac
+++ pork-0.99.8.1/configure.ac
@@ -114,6 +114,8 @@
 
 AC_CHECK_LIB(ncurses, resizeterm, AC_DEFINE(HAVE_RESIZETERM, 1, [Define to 1 if you have the 'resizeterm' function in -lncurses.]))
 
+AC_SEARCH_LIBS(stdscr, tinfo)
+
 AC_CHECK_TYPE(u_int32_t, uint32_t)
 if test "$ac_cv_type_u_int32_t" = "no"; then
 	AC_CHECK_TYPE(uint32_t, unsigned int)
--- pork-0.99.8.1/Makefile.am
+++ pork-0.99.8.1/Makefile.am
@@ -1,3 +1,5 @@
+AM_CFLAGS = -std=gnu89
+
 SUBDIRS = \
 	src			\
 	doc			\
--- pork-0.99.8.1/src/Makefile.am
+++ pork-0.99.8.1/src/Makefile.am
@@ -6,7 +6,7 @@
 endif
 
 
-AM_CFLAGS = -funsigned-char -Imissing -Wall -Iprotocols -fPIC
+AM_CFLAGS = -funsigned-char -Imissing -Wall -Iprotocols -fPIC -std=gnu89
 AM_CFLAGS += -DHELP_PATH=\"$(pkgdatadir)/help\" -DSYSTEM_PORKRC=\"$(pkgdatadir)/porkrc\"
 AM_CFLAGS += $(PERL_CFLAGS) $(DEBUG_CFLAGS)
 
--- pork-0.99.8.1/src/missing/Makefile.am
+++ pork-0.99.8.1/src/missing/Makefile.am
@@ -1,5 +1,5 @@
 INCLUDES = -I../../src
-AM_CFLAGS = $(DEBUG_CFLAGS) $(PERL_CFLAGS)
+AM_CFLAGS = $(DEBUG_CFLAGS) $(PERL_CFLAGS) -std=gnu89
 
 noinst_LIBRARIES = libmissing.a
 
--- pork-0.99.8.1/src/pork_inet.c
+++ pork-0.99.8.1/src/pork_inet.c
@@ -9,8 +9,9 @@
 
 #include <config.h>
 
-#include <unistd.h>
+#define _GNU_SOURCE 1
 #include <stdio.h>
+#include <unistd.h>
 #include <stdlib.h>
 #include <string.h>
 #include <errno.h>
--- pork-0.99.8.1/src/pork_screen_io.c
+++ pork-0.99.8.1/src/pork_screen_io.c
@@ -14,6 +14,8 @@
 
 #include <config.h>
 
+#define _GNU_SOURCE 1
+#include <stdio.h>
 #include <unistd.h>
 #include <ncurses.h>
 #include <stdlib.h>
--- pork-0.99.8.1/src/protocols/aim/Makefile.am
+++ pork-0.99.8.1/src/protocols/aim/Makefile.am
@@ -1,5 +1,5 @@
 INCLUDES = -I. -I.. -I../.. -I../../.. -I../../missing -Ilibfaim
-AM_CFLAGS = $(DEBUG_CFLAGS) $(PERL_CFLAGS)
+AM_CFLAGS = $(DEBUG_CFLAGS) $(PERL_CFLAGS) -std=gnu89
 
 noinst_LIBRARIES = libaim.a
 
--- pork-0.99.8.1/src/protocols/irc/Makefile.am
+++ pork-0.99.8.1/src/protocols/irc/Makefile.am
@@ -1,6 +1,6 @@
 INCLUDES = -I. -I.. -I../.. -I../../.. -I../../missing
 
-AM_CFLAGS = $(DEBUG_CFLAGS) $(PERL_CFLAGS)
+AM_CFLAGS = $(DEBUG_CFLAGS) $(PERL_CFLAGS) -std=gnu89
 
 noinst_LIBRARIES = libirc.a
 
--- pork-0.99.8.1/src/protocols/Makefile.am
+++ pork-0.99.8.1/src/protocols/Makefile.am
@@ -3,6 +3,6 @@
 endif
 
 INCLUDES = -I. -I.. -I../.. -I../missing
-AM_CFLAGS = $(DEBUG_CFLAGS) $(PERL_CFLAGS)
+AM_CFLAGS = $(DEBUG_CFLAGS) $(PERL_CFLAGS) -std=gnu89
 
 SUBDIRS = $(irc_dir) aim