[Rd] bin/Shlib overrides the variable PKG_LIBS from Makevars

[Mstislav Elagin]

Dear developers,

I have got a problem building my shared library via R CMD SHLIB (R
2.4.0 under WinXP), although it worked on R 2.3.0.

I tracked the problem down to the file $(R_HOME)/bin/Shlib that 
generates the variable PKG_LIBS and passes it to make on the command 
line thus overriding the value specified in Makevars.

I consider this behaviour a bug :), since it is apparently not 
documented and, moreover, "Writing R Extensions" states that PKG_LIBS 
may be used in Makevars to pass additional parameters to the linker.

Of course, it is possible to put my custom parameters in the variable
EXTRA_LIBS, but this way is not documented either.

WBR
Mstislav Elagin