Ensure that 'make install' works even if a file named 'install' exists.

Ensure that 'make install' works even if a file named 'install' exists.

Set PLUGIN_NAME from $PYTHON so that multi-Python builds do not collide.

This allows compiling a gcc-python-plugin to run in the context of across-compiler.  Using the cross-compiler to build gcc-python-pluginwould produce a plugin that cannot be loaded on the host system.

Replace "cp && sed -i" with "sed >", so that the file is written withthe desired values on the first pass.  Using a single sed reduces thenumber of processes and the number of complete file rewrites.

Use $(MAKE) to run the same make even when it is not named 'make' or isnot first on the path.  Use -C for simplicity, since the Makefilealready relies on GNU make extensions.

When GNU make is given the rule:    a b: $(DEPS)    commandThen for each target that needs an update, command will run.  If asingle run of command generates all the targets, then multiple runs areat best wasteful and at worst counterproductive if concurrent runs cancorrupt each other's output.

Change generation of print-gcc-version to preprocess, but not compile, adummy source file containing the macro GCC_VERSION, then scan theresulting output to find the numeric value of the macro.  This lets thecompiler do the work of expanding the expression, but avoids running atest program.  This is necessary for cross-compiler support, sincecross-compiled test outputs cannot be run locally.Store the output in autogenerated-gcc-version, since it is not arunnable program.

Rules in gcc-c-api assume the available ofautogenerated-EXTRA_CFLAGS.txt, so ensure it is generated beforerecursing into gcc-c-api, even in highly parallel workloads.

Generate to a temporary name, so that a failure in the script does notleave behind an up-to-date incomplete file.  If the script exitssuccessfully, then rename the file to its proper name.

Use $(filter-out) to eliminate autogenerated-casts.c from the generalrecipe, so that make does not warn when it encounters a specific recipefor autogenerated-casts.c.

Add a convenience function that knows not to quote the keyword NULL.

Instead of passing the contents of autogenerated-EXTRA_CFLAGS.txt on thegcc command line, read it in and use it to decide whether to run gcc org++.  This also produces a cleaner failure mode ifautogenerated-EXTRA_CFLAGS.txt has an unexpected value.

Rename GCC_VERSION to TARGET_GCC_VERSION in source files.  Add a commandline preprocessor definition setting TARGET_GCC_VERSION to the value ofthe file autogenerated-gcc-version, which contains the effectiveGCC_VERSION of TARGET_GCC.