Merge branch 'blas-pkgcfg' into release-3.13

Merge-request: !2631
diff --git a/Modules/FindBLAS.cmake b/Modules/FindBLAS.cmake
index efcf355..b5546e0 100644
--- a/Modules/FindBLAS.cmake
+++ b/Modules/FindBLAS.cmake
@@ -93,6 +93,7 @@
   find_package(PkgConfig)
   pkg_check_modules(PKGC_BLAS blas)
   if(PKGC_BLAS_FOUND)
+    set(BLAS_FOUND ${PKGC_BLAS_FOUND})
     set(BLAS_LIBRARIES "${PKGC_BLAS_LINK_LIBRARIES}")
     return()
   endif()