GitHub: Add more build types

- s/build.yml/${build}.yml/ for the existing builds

 - add filter on branches on push

 - add scan-build build triggered by pushes to the scan-build branch or by PRs
   that touch the scan-build.yml

 - add valgrind build triggered by pushes to the valgrind branch or by PRs that
   touch the valgrind.yml

.github/workflows/linux.yml

@@ -2,6 +2,9 @@ name: Linux Build
 
 on:
     push:
+      branches:
+         - 'master'
+         - 'heimdal-7-1-branch'
       paths:
          - '!docs/**'
          - '!**.md'
@@ -19,7 +22,7 @@ on:
          - '**/COPYING'
          - '**/INSTALL'
          - '**/README*'
-         - '.github/workflows/build.yml'
+         - '.github/workflows/linux.yml'
          - '!appveyor.yml'
          - '!.travis.yml'
 
@@ -41,7 +44,7 @@ on:
          - '**/COPYING'
          - '**/INSTALL'
          - '**/README*'
-         - '.github/workflows/build.yml'
+         - '.github/workflows/linux.yml'
          - '!appveyor.yml'
          - '!.travis.yml'
 
@@ -84,9 +87,6 @@ jobs:
                 make -j4
                 make check
                 make install
-            - name: Valgrind output
-              run: |
-                find . -name \*.log -print0|xargs -0 grep '^==[1-9]' || true
             - name: Core dump stacks
               run: |
                 echo "thread apply all bt" > /tmp/x