coin: Move cross-compilation build directories outside of sources

This stops confusing the 'reuse' tool when trying to generate a source
SBOM. The tool considers all files in the source dir as source files,
and because we placed the build dir inside the source dir, all build
files were considered source files. This caused errors saying the
files don't have copyright headers.

Change the build directory for cross-compilation jobs to be outside of
the source directory, similar how we do it for the native builds.

Augments ae62d90

Task-number: QTBUG-82820
Task-number: QTBUG-96513
Task-number: QTBUG-122899
Task-number: QTBUG-124453
Task-number: QTBUG-125211
Change-Id: Ie82a6c55aa5326f7e9cc5c0e09342f3405e78d17
Reviewed-by: Joerg Bornemann <joerg.bornemann@qt.io>
(cherry picked from commit fc08a07)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

coin/instructions/cmake_cross_compilation_module_build_instructions.yaml

@@ -17,16 +17,16 @@ instructions:
   - type: MakeDirectory
     directory: .git
   - type: MakeDirectory
-    directory: build
+    directory: "{{.SourceDir}}_build"
   - type: ChangeDirectory
-    directory: "{{.BuildDir}}/build"
+    directory: "{{.SourceDir}}_build"
   - type: MakeDirectory
     directory: target
   - type: EnvironmentVariable
     variableName: DESTDIR
     variableValue: ""
   - type: SetBuildDirectory
-    directory: "{{.SourceDir}}/build/target"
+    directory: "{{.SourceDir}}_build/target"
   - type: ChangeDirectory
     directory: "{{.BuildDir}}"
 

coin/instructions/cmake_cross_compilation_qtbase_build_instructions.yaml

@@ -3,16 +3,16 @@ instructions:
   - type: MakeDirectory
     directory: .git
   - type: MakeDirectory
-    directory: build
+    directory: "{{.SourceDir}}_build"
   - type: ChangeDirectory
-    directory: "{{.BuildDir}}/build"
+    directory: "{{.SourceDir}}_build"
   - type: MakeDirectory
     directory: target
   - type: EnvironmentVariable
     variableName: DESTDIR
     variableValue: ""
   - type: SetBuildDirectory
-    directory: "{{.SourceDir}}/build/target"
+    directory: "{{.SourceDir}}_build/target"
   - type: ChangeDirectory
     directory: "{{.BuildDir}}"