gh-96398: Detect emcc and mpicc in compiler names in configure (#117819)

- emcc defines __EMSCRIPTEN__
- mpicc doesn't define anything in particular; detect it using basename

Author: erlend-aasland

configure

@@ -992,7 +992,9 @@ dnl check for GCC last, other compilers set __GNUC__, too.
 dnl msvc is listed for completeness.
 AC_CACHE_CHECK([for CC compiler name], [ac_cv_cc_name], [
 cat > conftest.c <<EOF
-#if defined(__INTEL_COMPILER) || defined(__ICC)
+#if defined(__EMSCRIPTEN__)
+  emcc
+#elif defined(__INTEL_COMPILER) || defined(__ICC)
   icc
 #elif defined(__ibmxl__) || defined(__xlc__) || defined(__xlC__)
   xlc
@@ -1009,6 +1011,9 @@ EOF
 
 if $CPP $CPPFLAGS conftest.c >conftest.out 2>/dev/null; then
   ac_cv_cc_name=`grep -v '^#' conftest.out | grep -v '^ *$' | tr -d ' 	'`
+  if $(expr "//$CC" : '.*/\(.*\)') = "mpicc"; then
+    ac_cv_cc_name="mpicc"
+  fi
 else
   ac_cv_cc_name="unknown"
 fi