Install Apache 2.4.20 on Solaris 10 --- Error "ld: fatal: file ab.o: wrong ELF class: ELFCLASS32"

I am following the "Compilling and Installing" guide from Apache > HTTP Server > Documentation > Version 2.4 page

The configure running OK:

# export CC="gcc -m64"
# ./configure \
--prefix=/usr/local/apache2/httpd-2.4.20 \
--with-port=80 \
--with-mpm=worker \
--enable-mods-shared=most \
--enable-ssl \
--with-ssl=/usr/local/ssl \
--enable-proxy \
--disable-example \
--with-included-apr \
--with-pcre=/usr/local/apache2/pcre2/bin/pcre2-config 

But got a fatal error when run make:

# make
....
....
Making all in generators
Making all in dav/fs
Making all in mappers
Making all in support
/usr/local/apache2/install/httpd-2.4.20/srclib/apr/libtool --silent --mode=link gcc -m64 -std=gnu99  -g -O2   -L/usr/local/ssl/lib -lssl -lcrypto -luuid -lsendfile -lrt -lsocket -lnsl -lpthread  \
         -o ab  ab.lo      /usr/local/apache2/install/httpd-2.4.20/srclib/apr-util/libaprutil-1.la -lexpat /usr/local/apache2/install/httpd-2.4.20/srclib/apr/libapr-1.la -luuid -lsendfile -lrt -lsocket -lnsl -lpthread -lm
ld: fatal: file ab.o: wrong ELF class: ELFCLASS32
ld: fatal: file processing errors. No output written to .libs/ab
collect2: ld returned 1 exit status
*** Error code 1
make: Fatal error: Command failed for target `ab'
Current working directory /usr/local/apache2/install/httpd-2.4.20/support
*** Error code 1
The following command caused the error:
otarget=`echo all-recursive|sed s/-recursive//`; \
list='  '; \
for i in $list; do \
.....
.....

After searching online, I think the issue is related to the 32-bit class (ELFCLASS32). I am trying to add some compile/link flags. But there are many options to try. Is there anyone have this experience? Thank you very much if you can give my any hint or clue.

I have a screen capture (text file) of the configure and make. Please see the attachment.