Something

checking sys/times.h presence... yes
checking for sys/times.h... yes
checking for int... (cached) yes
checking size of int... (cached) 4
checking for short... yes
checking size of short... configure: error: cannot compute sizeof (short), 77
See `config.log' for more details.

!!! ERROR: dev-lang/php-5.1.6-r4 failed.
Call stack:
  ebuild.sh, line 1546:   Called dyn_compile
  ebuild.sh, line 937:   Called src_compile
  php-5.1.6-r4.ebuild, line 173:   Called src_compile_normal
  php-5.1.6-r4.ebuild, line 323:   Called php5_1-sapi_src_compile
  php5_1-sapi.eclass, line 575:   Called die

/etc/make.conf
CFLAGS="-O2 -march=i686 -pipe"
CHOST="i686-pc-linux-gnu"
CXXFLAGS="${CFLAGS}"

[ebuild   R   ] dev-lang/php-5.1.6-r4  USE="apache2 berkdb bzip2 cli crypt curl doc ftp* gd gdbm iconv ldap mysql mysqli ncurses nls pcre posix readline reflection sasl session sharedext sockets spell spl ssl threads truetype unicode xml zlib -adabas -apache* -bcmath -birdstep -calendar* -cdb -cgi -cjk -concurrentmodphp -ctype -curlwrappers -db2 -dbase -dbmaker -debug -discard-path -empress -empress-bcs -esoob -exif -fastbuild -fdftk -filepro -firebird -flatfile -force-cgi-redirect -frontbase -gd-external -gmp -hardenedphp -hash -hyperwave-api -imap* -informix -inifile -interbase -iodbc -ipv6 -java-external -kerberos -libedit -mcve -memlimit -mhash -ming -msql -mssql -oci8 -oci8-instant-client -odbc -pcntl -pdo -pdo-external -pic -postgres -qdbm -recode -sapdb -sharedmem -simplexml -snmp -soap -solid -sqlite -sybase -sybase-ct -sysvipc -tidy -tokenizer -vm-goto -vm-switch -wddx -xmlreader -xmlrpc -xmlwriter -xpm -xsl -yaz -zip"