building with libtool fails on Ubuntu 10.04

[Even Rouault]

After the update to libtool 2.4, configure --with-libtool fails with

/bin/sh /opt/gdal/trunk/libtool --mode=compile --tag=CXX g++ -g -O2  -Wall  -DOGR_ENABLED -I/opt/gdal/trunk/port          -DHAVE_CURL -DHAVE_LIBZ -c -o cpl_conv.lo cpl_conv.cpp
/opt/gdal/trunk/libtool: 1656: preserve_args+= --tag CXX: not found
eval: 1: base_compile+= g++: not found
eval: 1: base_compile+= -g: not found
eval: 1: base_compile+= -O2: not found
eval: 1: base_compile+= -Wall: not found
eval: 1: base_compile+= -DOGR_ENABLED: not found
eval: 1: base_compile+= -I/opt/gdal/trunk/port: not found
eval: 1: base_compile+= -DHAVE_CURL: not found
eval: 1: base_compile+= -DHAVE_LIBZ: not found
eval: 1: base_compile+= -c: not found
libtool: compile: you must specify a compilation command
libtool: compile: Try `libtool --help --mode=compile' for more information.
make[1]: *** [cpl_conv.lo] Error 1
make[1]: Leaving directory `/opt/gdal/trunk/port'
make: *** [port-target] Error 2

It turns out that in GDALmake.opt we have :

LIBTOOL = $(SHELL) $(top_builddir)/libtool

but $(SHELL) is not set and default to /bin/sh, which is not bash on Ubuntu 10.04, but new libtool requires a shell with bachisms.

The solution is to add a SHELL = @SHELL@ so that the variable gets substituated.

[Even Rouault]

r22467 /trunk/gdal/GDALmake.opt.in: Fix building with libtool (#4102)

[Even Rouault]

I have tested on various VMs and it seems to do the trick. And, on OpenSolaris clone, the hack indicated in the GDALmake.opt is no longer necessary