Merge branch '8-gsl-2-5-with-gcc-7-4-0-and-8-3-0' into 'master'

Resolve "gsl 2.5 with gcc 7.4.0 and 8.3.0"

Closes #8

See merge request Pmodules/buildblocks!7

Compiler/gsl/files/variants

@@ -13,3 +13,18 @@ gsl/1.16             stable	gcc/4.8.5
 gsl/1.16             stable	gcc/4.9.4 
 gsl/1.16             stable	gcc/5.4.0 
 gsl/1.16             stable	gcc/6.2.0 
+gsl/2.2.1       stable		gcc/4.8.5 
+gsl/2.2.1       stable		gcc/4.9.4 
+gsl/2.2.1       stable		gcc/5.4.0 
+gsl/2.2.1       stable		gcc/6.2.0 
+gsl/2.2.1       stable		gcc/6.3.0 
+
+gsl/2.4		stable		gcc/5.5.0 
+gsl/2.4		stable		gcc/6.4.0 
+gsl/2.4		stable		gcc/7.3.0 
+gsl/2.4		stable		clang-macos/9.0.0
+gsl/2.4		stable		intel/17.4
+
+gsl/2.5		stable		gcc/7.3.0 
+gsl/2.5		stable		gcc/7.4.0 
+gsl/2.5		stable		gcc/8.3.0