build minor problems: Compilation Flags, makeinfo

[Yotam Medini]

Build minor problems:

* Compilation flags
===================
Seems like setting  CXXFLAGS=-O2  USER_CXXFLAGS=-O2  environment variables
are considered by ./configure. But later compilation 
uses also also '-g'.
Actually '-O2' is specified twice.

For example:

  rm -f ./out/dstream.dep; DEPENDENCIES_OUTPUT="./out/dstream.dep
   ./out/dstream.o" c++ -c -DHAVE_CONFIG_H -Iinclude -I./out
   -I.././lib/include -I../lib/./out -I.././flower/include
   -I../flower/./out -O2 -finline-functions -O2 -g -I/home/local/include
   -Wall -W -Wmissing-prototypes -Wconversion dstream.cc -o out/dstream.o

* Documentation
===============
...
makeinfo  out/lilypond.texi -o out/lilypond.info
./out/lilypond.texi:85: Next field of node `Top' not pointed to.
./out/lilypond.texi:129: This node (Tutorial) has the bad Prev.
makeinfo: Removing output file `out/lilypond.info' due to errors; use --force 
to preserve.
make[3]: *** [out/lilypond.info] Error 2
make[3]: Leaving directory 
`/home/local/src/lilypond/lilypond-1.3.122/Documentation/user'
....

-- yotam