Update configure file

[csepanda]

• Add env rule to set protocol version one time per build;
• Add variables to Makefile instead of plain substitute from
  configure. It improves readability of generated Makefile;
• Add commentaries to some parts of scripts;

[ValeriyKr]

Make it work on Solaris 10, please.

[csepanda]

Works in SunOS as well as in GNU/Linux

Now it is working on Solaris 10

[ValeriyKr]

Make it work on FreeBSD, please.

10:14pm kk at kkbsd /tmp $?:0                                                           
% git clone https://github.com/csepanda/itmmorgue
Cloning into 'itmmorgue'...
remote: Counting objects: 1300, done.
remote: Compressing objects: 100% (24/24), done.
Receiving objects:  52% (676/1300), 124.01 KiB | 112.00 KiB/s   B/s   
remote: Total 1300 (delta 8), reused 18 (delta 3), pack-reused 1273
Receiving objects: 100% (1300/1300), 250.96 KiB | 112.00 KiB/s, done.
Resolving deltas: 100% (849/849), done.

10:14pm kk at kkbsd /tmp $?:0                                                           
% cd itmmorgue/
10:14pm kk at kkbsd /tmp/itmmorgue $?:0                                                 
% git submodule update --init
Submodule 'lib/trie' (https://github.com/ValeriyKr/trie) registered for path 'lib/trie'
Cloning into '/tmp/itmmorgue/lib/trie'...
Submodule path 'lib/trie': checked out '4c396cda02ce0e7194d0831fe922c86d00550a9c'
10:15pm kk at kkbsd /tmp/itmmorgue $?:0                                                 
% git checkout build-configuration
Branch build-configuration set up to track remote branch build-configuration from origin.
Switched to a new branch 'build-configuration'
10:15pm kk at kkbsd /tmp/itmmorgue $?:0                                                 
% ./configure 
Checking C compiler...cc
Checking CFLAGS...OK
Checking for ncursesw...OK
Checking -Wimplicit-fallthrough...FAIL
Checking lib/trie/Makefile...OK
Successfully configured for FreeBSD. Please run 'make' now.
10:15pm kk at kkbsd /tmp/itmmorgue $?:0                                                 
% make
syntax error at -e line 1, near "+="
Execution of -e aborted due to compilation errors.
make: "/tmp/itmmorgue/Makefile" line 9: warning: "perl -lne ' +=  +  for split//; END{print }' src/*" returned non-zero status
cc --std=gnu99 -pedantic -Wall -Wextra -Werror -ggdb3 -Ilib -D_DEBUG -pthread -DPROTOCOL_VERSION= -c src/event.c -o bin/event.o
cc --std=gnu99 -pedantic -Wall -Wextra -Werror -ggdb3 -Ilib -D_DEBUG -pthread -DPROTOCOL_VERSION= -c src/player.c -o bin/player.o
cc --std=gnu99 -pedantic -Wall -Wextra -Werror -ggdb3 -Ilib -D_DEBUG -pthread -DPROTOCOL_VERSION= -c src/tiles.c -o bin/tiles.o
cc --std=gnu99 -pedantic -Wall -Wextra -Werror -ggdb3 -Ilib -D_DEBUG -pthread -DPROTOCOL_VERSION= -c src/levels.c -o bin/levels.o
cc --std=gnu99 -pedantic -Wall -Wextra -Werror -ggdb3 -Ilib -D_DEBUG -pthread -DPROTOCOL_VERSION= -c src/connection.c -o bin/connection.o
cc --std=gnu99 -pedantic -Wall -Wextra -Werror -ggdb3 -Ilib -D_DEBUG -pthread -DPROTOCOL_VERSION= -c src/sysmsg.c -o bin/sysmsg.o
cc --std=gnu99 -pedantic -Wall -Wextra -Werror -ggdb3 -Ilib -D_DEBUG -pthread -DPROTOCOL_VERSION= -c src/protocol.c -o bin/protocol.o
src/protocol.c:42:40: error: expected expression
    mbuf.msg.version = PROTOCOL_VERSION;
                                       ^
1 error generated.
*** Error code 1

Stop.
make: stopped in /tmp/itmmorgue
10:15pm kk at kkbsd /tmp/itmmorgue $?:1                                                 
% make clean
syntax error at -e line 1, near "+="
Execution of -e aborted due to compilation errors.
make: "/tmp/itmmorgue/Makefile" line 9: warning: "perl -lne ' +=  +  for split//; END{print }' src/*" returned non-zero status
rm -rf bin
rm -f lib/trie/trie.o

[zhmylove]

@csepanda как подвижки с перепиливанием ЭТОГО под FreeBSD, не потеряв compatibility с Solaris 10 & GNU/Linux?