Get rid of AC_CHECK_LIB(m, pow) since this is taken care of later with

LIBM (from --with-libm=...); this actually broke the customizability
offered by the latter option.  Thanks go to Clay Spence for reporting
this.

configure.in

@@ -537,7 +537,6 @@ AC_MSG_RESULT($LINKFORSHARED)
 # checks for libraries
 AC_CHECK_LIB(dl, dlopen)	# Dynamic linking for SunOS/Solaris and SYSV
 AC_CHECK_LIB(dld, shl_load)	# Dynamic linking for HP-UX
-AC_CHECK_LIB(m, pow)		# Std math lib -- assume needed if it exists
 # Most SVR4 platforms (e.g. Solaris) need -lsocket and -lnsl.
 # However on SGI IRIX, these exist but are broken.
 # BeOS' sockets are stashed in libnet.