[GR-44872] Windows environment variables are case insensitive and result in native build failures

[zakkak]

Environment variable names are case insensitive on windows, so both $Env:Path and $Env:PATH in powershell evaluate to the same value, and in some cases Windows will use Path and in others PATH as the variable name in the environemnt...

GraalVM, however, only requires/propagates the uppercase PATH environment variable, which results in the following failure (originally reported in graalvm#483) when Windows use Path as the variable name:

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GraalVM Native Image: Generating 'quarkus-integration-test-resteasy-jackson-999-SNAPSHOT-runner' (executable)...
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[1/8] Initializing...                                                                                    (0.0s @ 0.22GB)
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                         0.7s (6.8% of total time) in 8 GCs | Peak RSS: 0.57GB | CPU load: 1.88
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Produced artifacts:
 D:\a\mandrel\mandrel\quarkus\integration-tests\resteasy-jackson\target\quarkus-integration-test-resteasy-jackson-999-SNAPSHOT-native-image-source-jar\svm_err_b_20230311T033426.745_pid1380.md (build_info)
========================================================================================================================
Failed generating 'quarkus-integration-test-resteasy-jackson-999-SNAPSHOT-runner' after 8.7s.

The build process encountered an unexpected error:

java.lang.NullPointerException: Cannot invoke "String.split(String)" because the return value of "java.lang.System.getenv(String)" is null
	at org.graalvm.nativeimage.builder/com.oracle.svm.hosted.c.codegen.CCompilerInvoker.lookupSearchPath(CCompilerInvoker.java:515)
	at org.graalvm.nativeimage.builder/com.oracle.svm.hosted.c.codegen.CCompilerInvoker.getCCompilerPath(CCompilerInvoker.java:528)
	at org.graalvm.nativeimage.builder/com.oracle.svm.hosted.c.codegen.CCompilerInvoker.getCCompilerInfo(CCompilerInvoker.java:372)
	at org.graalvm.nativeimage.builder/com.oracle.svm.hosted.c.codegen.CCompilerInvoker.<init>(CCompilerInvoker.java:71)
	at org.graalvm.nativeimage.builder/com.oracle.svm.hosted.c.codegen.CCompilerInvoker$WindowsCCompilerInvoker.<init>(CCompilerInvoker.java:111)
	at org.graalvm.nativeimage.builder/com.oracle.svm.hosted.c.codegen.CCompilerInvoker.create(CCompilerInvoker.java:85)
	at org.graalvm.nativeimage.builder/com.oracle.svm.hosted.NativeImageGenerator.setupNativeImage(NativeImageGenerator.java:920)
	at org.graalvm.nativeimage.builder/com.oracle.svm.hosted.NativeImageGenerator.doRun(NativeImageGenerator.java:576)
	at org.graalvm.nativeimage.builder/com.oracle.svm.hosted.NativeImageGenerator.run(NativeImageGenerator.java:536)
	at org.graalvm.nativeimage.builder/com.oracle.svm.hosted.NativeImageGeneratorRunner.buildImage(NativeImageGeneratorRunner.java:408)
	at org.graalvm.nativeimage.builder/com.oracle.svm.hosted.NativeImageGeneratorRunner.build(NativeImageGeneratorRunner.java:612)
	at org.graalvm.nativeimage.builder/com.oracle.svm.hosted.NativeImageGeneratorRunner.start(NativeImageGeneratorRunner.java:134)
	at org.graalvm.nativeimage.builder/com.oracle.svm.hosted.NativeImageGeneratorRunner.main(NativeImageGeneratorRunner.java:94)

cc @jerboaa