ortep3: fix errorneous lines in graphics output

-O2 optimization creates wrong overlap of lines calculations.

science/ortep3/Portfile

@@ -5,7 +5,7 @@ PortGroup           compilers 1.0
 
 name                ortep3
 version             1.0.3
-revision            1
+revision            2
 categories          science chemistry
 license             public-domain
 maintainers         {@kamischi web.de:karl-michael.schindler} openmaintainer
@@ -61,10 +61,11 @@ post-patch {
 
 use_parallel_build  no
 
+# Note: Not setting -O0 leads to errorneous lines in the graphics
 build {
     system -W ${worksrcpath} "${configure.f90} \
         -fdiagnostics-color=auto -std=legacy  \
-        -O2 \
+        -O0 \
         -F${frameworks_dir} -framework AquaTerm \
         -L${prefix}/lib \
         -lpng -lpgplot -lX11 \