move blas handling to build/pkgs/

also, make atlas as not installable if openblas
is going to be used, and the other way around

build/pkgs/atlas/spkg-configure.m4

@@ -0,0 +1,8 @@
+SAGE_SPKG_CONFIGURE([atlas], [dnl use old test/installation procedure with env. variables
+    sage_spkg_install_atlas=yes
+    ], [
+    AC_REQUIRE([SAGE_SPKG_CONFIGURE_OPENBLAS])
+    AS_IF([test x"$with_blas" = xatlas], [
+      sage_require_openblas=no
+      sage_require_atlas=yes]) 
+])

build/pkgs/openblas/spkg-configure.m4

@@ -10,6 +10,23 @@ SAGE_SPKG_CONFIGURE([openblas], [
        ])
     ], [sage_spkg_install_openblas=yes])
   ], [
-  AS_IF([test "x$with_blas" = xopenblas], [sage_require_openblas=yes])
+  AS_IF([test "x$with_blas" = xopenblas], [
+     sage_require_openblas=yes
+     sage_require_atlas=no])
+  ], [
+  AC_MSG_CHECKING([BLAS library])
+  AC_ARG_WITH([blas],
+  [AS_HELP_STRING([--with-blas=openblas],
+    [use OpenBLAS as BLAS library (default)])]
+  [AS_HELP_STRING([--with-blas=atlas],
+    [use ATLAS as BLAS library])],,
+    [with_blas=openblas]  # default
+  )
+  AS_CASE(["$with_blas"],
+    [openblas], [],
+    [atlas],    [sage_spkg_install_openblas=no],
+                [AC_MSG_ERROR([allowed values for --with-blas are 'atlas' and 'openblas'])])
+  AC_MSG_RESULT([$with_blas])
+  AC_SUBST([SAGE_BLAS], [$with_blas])
   ]
 )

configure.ac

@@ -400,25 +400,6 @@ esac
 AC_MSG_RESULT([$SAGE_PYTHON_VERSION])
 AC_SUBST(SAGE_PYTHON_VERSION)
 
-# BLAS library
-AC_MSG_CHECKING([BLAS library])
-AC_ARG_WITH([blas],
-[AS_HELP_STRING([--with-blas=openblas],
-    [use OpenBLAS as BLAS library (default)])]
-[AS_HELP_STRING([--with-blas=atlas],
-    [use ATLAS as BLAS library])],,
-    [with_blas=openblas]  # default
-)
-
-case "$with_blas" in
-    openblas) true;;
-    atlas) sage_spkg_install_openblas=no;;
-    *) AC_MSG_ERROR([allowed values for --with-blas are 'atlas' and 'openblas']);;
-esac
-
-AC_MSG_RESULT([$with_blas])
-AC_SUBST([SAGE_BLAS], [$with_blas])
-
 # $(TOOLCHAIN) variable containing prerequisites for the build
 SAGE_TOOLCHAIN=gcc
 if test "$SAGE_INSTALL_CCACHE" = yes ; then