Fix use of M4

Author: j-woz

dev/conda/settings.sed

@@ -9,7 +9,7 @@ s@ENABLE_PYTHON=0@ENABLE_PYTHON=1@
 s@PYTHON_EXE=""@PYTHON_EXE="$PYTHON"@
 s@PARALLELISM=.*@PARALLELISM=4@
 s@ENABLE_CONDA_LINUX=.*@ENABLE_CONDA_LINUX="$ENABLE_CONDA_LINUX"@
-m4_ifelse(getenv(ENABLE_R),`1',m4_include(settings-R.sed))
+m4_ifelse(m4_getenv(ENABLE_R),`1',m4_include(settings-R.sed))
 
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