* C code
    + Kurt Hornik noted: PBSddesolve_1.12.5.tar.gz still seems to fail to install with gcc10.
      - Added -fno-common in various lines of Rdev's Makeconf files to check for duplicate declarations
      -  (as per R-extensions: https://cran.r-project.org/doc/manuals/r-devel/R-exts.html#Common-symbols)
      - CFLAGS = -O2 -Wall $(DEBUGFLAG) -std=gnu99 -mtune=generic -fno-common
      - CXX11FLAGS = -O2 -Wall $(DEBUGFLAG) -mtune=generic -fno-common
      - CXX14FLAGS = -O2 -Wall $(DEBUGFLAG) -mtune=generic -fno-common
      - Rdevcheck fails when lines `globaldatatype global_data; globalRdatatype r_stuff;' appear in both `PBSddesolve.c' and `R-model.c'.
      - Removed the declaration in 'r_model.c' and the check works OK, the build works OK, and the examples work.
      - ACB approves changes.