ci: try to get linux cross-compilation working

.github/workflows/ci.yml

@@ -1,4 +1,4 @@
-name: CI
+name: Tests
 
 env:
   GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}

.github/workflows/extensions.yml

@@ -42,13 +42,23 @@ jobs:
         Copy-Item sqlite-amalgamation-3470200\sqlite3.h .
         Copy-Item sqlite-amalgamation-3470200\sqlite3ext.h .
 
-    - name: Debug uname -m
-      if: runner.os != 'Windows'
-      run: uname -m
+    - name: Set up QEMU (Linux cross-compilation)
+      if: runner.os == 'Linux' && matrix.arch == 'ARM64'
+      uses: docker/setup-qemu-action@v3
 
     - name: Build C files
+      if: ! (runner.os == 'Linux' && matrix.arch == 'ARM64')
       run: cd extensions && make
 
+    - name: Build C files (Linux cross-compilation)
+      if: runner.os == 'Linux' && matrix.arch == 'ARM64'
+      run:
+        cd extensions
+        docker run --platform linux/arm64 \
+          -v .:/extensions \
+          debian:slim \
+          bash -c "apt-get update && apt-get install -y make gcc && cd /extensions && make"
+
     - name: Commit output files
       shell: bash
       run: |

.github/workflows/validate.yml

@@ -1,3 +1,5 @@
+name: Validate code
+
 on: [push, pull_request]
 
 jobs:

extensions/Makefile

@@ -4,11 +4,11 @@ OUTPUT :=
 
 ifeq ($(OS),Windows_NT)
 	OUTPUT = lib/noattach.dll
-	CCFLAGS = -shared -Wl,--exclude-libs,ALL
+	CCFLAGS += -shared -Wl,--exclude-libs,ALL
 	CC = clang
 else
 	UNAME := $(shell uname)
-	CCFLAGS = -fPIC -Os -shared
+	CCFLAGS += -fPIC -Os -shared
 	ifeq ($(UNAME),Darwin)
 		ifeq ($(shell uname -m),arm64)
 			OUTPUT = lib/arm/noattach.dylib