Quick pidgin on Solaris question

[Mauricio Tavares]

What does this error mean?

raub at abaco pidgin-2.7.3> ./configure GLIB_CFLAGS="-I/usr/local/include" 
GLIB_LIBS="-L/usr/local/lib" IDN_CFLAGS="-I/usr/local/include" 
IDN_LIBS="-L/usr/local/lib" DBUS_CFLAGS="-I/usr/local/include" 
DBUS_LIBS="-L/usr/local/lib" --disable-gtkui --disable-gstreamer 
--disable-vv --disable-meanwhile --disable-avahi --disable-nm
checking build system type... sparc-sun-solaris2.10
checking host system type... sparc-sun-solaris2.10
checking for a BSD-compatible install... /usr/local/bin/install -c
checking whether build environment is sane... yes
checking for gawk... no
checking for mawk... no
checking for nawk... nawk
checking whether make sets $(MAKE)... yes
checking for sed... /usr/bin/sed
checking for gcc... gcc
checking whether the C compiler works... yes
checking for C compiler default output file name... a.out
[...]
checking for pthread_create in -lpthread... yes
checking for openpty in -lutil... no
checking for dbopen in -ldb... no
checking for Python compile flags... ok
checking for perl... /usr/bin/perl
checking for Perl compile flags... ok
checking for libperl... checking for perl_run... yes
checking EXTERN.h usability... no
checking EXTERN.h presence... yes
configure: WARNING: EXTERN.h: present but cannot be compiled
configure: WARNING: EXTERN.h:     check for missing prerequisite headers?
configure: WARNING: EXTERN.h: see the Autoconf documentation
configure: WARNING: EXTERN.h:     section "Present But Cannot Be Compiled"
configure: WARNING: EXTERN.h: proceeding with the compiler's result
configure: WARNING:     ## ------------------------------ ##
configure: WARNING:     ## Report this to devel at pidgin.im ##
configure: WARNING:     ## ------------------------------ ##
checking for EXTERN.h... no
checking for perl.h... no
configure: error:
Perl development headers not found.
Use --disable-perl if you do not need Perl scripting support.

raub at abaco pidgin-2.7.3> which perl
/usr/bin/perl
raub at abaco pidgin-2.7.3>