rgl build warnings and loading error on Linux

 I have several problems in using rgl-0.77 (and recent earlier
 versions) on Gentoo Linux with a custom-built v. 2.6.22 kernel.
 Currently I use R-2.6.1.

 When I build rgl,
 # R CMD INSTALL "/home/liviu/inst/dwn/R/rgl_0.77.tar.gz"
 or
 install.packages("rgl", dependencies=TRUE, method ="wget"),

 I notice the following warning messages:
 i686-pc-linux-gnu-g++ -I/usr/lib/R/include -I/usr/lib/R/include
 -I/usr/local/include    -fpic  -O2 -march=pentium-m -pipe
 -fomit-frame-pointer -std=gnu99 -c api.cpp -o api.o
 cc1plus: warning: command line option "-std=gnu99" is valid for C/ObjC
 but not for C++

 The warning message itself is repeated during the entire build
 process. However, the package builds fine, but fails to load:

 > library(rgl)

 Error in dyn.load(file, ...) :
  unable to load shared library '/usr/lib/R/library/rgl/libs/rgl.so':
  /usr/lib/R/library/rgl/libs/rgl.so: undefined symbol: glTexCoordPointer
 Error : .onLoad failed in 'loadNamespace' for 'rgl'
 Error: package/namespace load failed for 'rgl'

 I had the exact same error message with rgl_0.76.

 Could anyone suggest how to make rgl build correctly?