How to debug Symbol not found: ___exp10

I am compiling my own web server using the following:

• curl-7.43.0
• HTTPD-2.4.12
• jpegsrc.v9
• Libpng-1.6.18
• libxml2-2.9.2
• PCRE-8.37
• PHP-5.4.43

I have no problem with MacOS 10.9, but I ran into this error on MacOS 10.8:

httpd: Syntax error on line 18 of /Webserver/httpd-2.4.12/conf/httpd.conf:  
Cannot load modules/libphp5.so into server: dlopen(/Webserver/httpd/modules/libphp5.so,10): Symbol not found:___exp10  
  Referenced from: /Webserver/libxml2-2.9.2/lib/libxml2.2.dylib  
  Expected in: /usr/lib/libSystem.B.dylib  
in /Webserver/libxml2-2.9.2/lib/libxml2.2.dylib

      

        
        
        
      

    

Wondering how to debug this?
I've already used otool -L

, but I have to admit I don't know how to interpret the results:

> otool -L /Webserver/httpd/modules/libphp5.so
/Webserver/httpd/modules/libphp5.so:
    /Webserver/httpd-2.4.12/lib/libaprutil-1.0.dylib (compatibility version 6.0.0, current version 6.4.0)
    /usr/lib/libexpat.1.dylib (compatibility version 7.0.0, current version 7.2.0)
    /usr/lib/libiconv.2.dylib (compatibility version 7.0.0, current version 7.0.0)
    /Webserver/httpd-2.4.12/lib/libapr-1.0.dylib (compatibility version 6.0.0, current version 6.2.0)
    /usr/lib/libSystem.B.dylib (compatibility version 1.0.0, current version 1197.1.1)
    /usr/lib/libz.1.dylib (compatibility version 1.0.0, current version 1.2.5)
    /usr/lib/libresolv.9.dylib (compatibility version 1.0.0, current version 1.0.0)
    /Webserver/libpng-1.6.18/lib/libpng16.16.dylib (compatibility version 35.0.0, current version 35.0.0)
    /Webserver/jpeg-9/lib/libjpeg.9.dylib (compatibility version 10.0.0, current version 10.0.0)
    /Webserver/curl-7.43.0/lib/libcurl.4.dylib (compatibility version 8.0.0, current version 8.0.0)
    /usr/lib/libcrypto.0.9.8.dylib (compatibility version 0.9.8, current version 0.9.8)
    /usr/lib/libssl.0.9.8.dylib (compatibility version 0.9.8, current version 0.9.8)
    /Webserver/libxml2-2.9.1/lib/libxml2.2.dylib (compatibility version 12.0.0, current version 12.1.0)
    /System/Library/Frameworks/LDAP.framework/Versions/A/LDAP (compatibility version 1.0.0, current version 2.4.0)

> otool -L /Webserver/libxml2-2.9.1/lib/libxml2.2.dylib
/Webserver/libxml2-2.9.1/lib/libxml2.2.dylib:
    /Webserver/libxml2-2.9.1/lib/libxml2.2.dylib (compatibility version 12.0.0, current version 12.1.0)
    /usr/lib/libSystem.B.dylib (compatibility version 1.0.0, current version 1197.1.1)
    /usr/lib/libz.1.dylib (compatibility version 1.0.0, current version 1.2.5)
    /usr/lib/libiconv.2.dylib (compatibility version 7.0.0, current version 7.0.0)

      

        
        
        
      

    

What tools can I use?

Regards, Arnaud