openblas: use "all" target since it's marked sequential (#35905)

openblas likes to concurrently writes to the same archive from different
targets, and solves that through .NOTPARALLEL: all

We run `make x y z` which is not affected by `NOTPARALLEL`, running into
races.

var/spack/repos/builtin/packages/openblas/fix-shared-tests-prereqs.patch

@@ -1,14 +0,0 @@
-diff --git a/Makefile b/Makefile
-index 967ab1bb6..98666e853 100644
---- a/Makefile
-+++ b/Makefile
-@@ -42,6 +42,9 @@ SUBDIRS_ALL = $(SUBDIRS) test ctest utest exports benchmark ../laswp ../bench cp
- .PHONY : all libs netlib $(RELA) test ctest shared install
- .NOTPARALLEL : all libs $(RELA) prof lapack-test install blas-test
- 
-+shared: libs netlib $(RELA)
-+tests: libs netlib $(RELA) shared
-+
- all :: libs netlib $(RELA) tests shared
- 	@echo
- 	@echo " OpenBLAS build complete. ($(LIB_COMPONENTS))"

var/spack/repos/builtin/packages/openblas/package.py

@@ -182,10 +182,6 @@ class Openblas(MakefilePackage):
         when="@0.3.21 %gcc@:9",
     )
 
-    # Generic fix (https://github.com/xianyi/OpenBLAS/pull/3902) so we don't
-    # have to build tests
-    patch("fix-shared-tests-prereqs.patch", when="@0.2.20:0.3.21")
-
     # See https://github.com/spack/spack/issues/19932#issuecomment-733452619
     # Notice: fixed on Amazon Linux GCC 7.3.1 (which is an unofficial version
     # as GCC only has major.minor releases. But the bound :7.3.0 doesn't hurt)
@@ -452,13 +448,7 @@ def libs(self):
 
     @property
     def build_targets(self):
-        targets = ["libs", "netlib"]
-
-        # Build shared if variant is set.
-        if "+shared" in self.spec:
-            targets += ["shared"]
-
-        return self.make_defs + targets
+        return self.make_defs + ["all"]
 
     @run_after("build")
     @on_package_attributes(run_tests=True)