[petsc-dev] fix conflict between triangle and spai

[Satish Balay via petsc-dev]

I get the following error with triangle+spai build with gcc-10 [this is on 
linux though - ignore osx in PETSC_ARCH]

     CLINKER arch-ci-osx-cxx-pkgs-opt/lib/libpetsc.so.3.13.0
/usr/bin/ld: 
/home/balay/petsc/arch-ci-osx-cxx-pkgs-opt/lib/libtriangle.a(triangle.o):/home/balay/petsc/arch-ci-osx-cxx-pkgs-opt/externalpackages/Triangle/src/triangle.c:667:
 multiple definition of `epsilon'; 
/home/balay/petsc/arch-ci-osx-cxx-pkgs-opt/lib/libspai.a(spai.o):(.bss+0x188): 
first defined here


Matt,

Any objection to this change to triangle?

diff --git a/src/triangle.c b/src/triangle.c
index 8e915a1..76f6d84 100644
--- a/src/triangle.c
+++ b/src/triangle.c
@@ -664,7 +664,7 @@ long samples;                /* Number of random samples 
for point location. */
 unsigned long randomseed;                     /* Current random number seed. */
 
 REAL splitter;       /* Used to split REAL factors for exact multiplication. */
-REAL epsilon;                             /* Floating-point machine epsilon. */
+static REAL epsilon;                      /* Floating-point machine epsilon. */
 REAL resulterrbound;
 REAL ccwerrboundA, ccwerrboundB, ccwerrboundC;
 REAL iccerrboundA, iccerrboundB, iccerrboundC;

Satish