[Flang] Add -fintrinsic-modules-path= alias (#149417)

Add the syntax `-fintrinsic-modules-path=<dir>` as an alias to the
existing option `-fintrinsic-modules-path <dir>`. gfortran also supports
both alternatives.

This is particularly useful with CMake which de-duplicates command-line
options. For instance,
`-fintrinsic-modules-path /path/A -fintrinsic-modules-path /path/B`
is de-duplicated to
`-fintrinsic-modules-path /path/A /path/B`
since it conisiders the second `-fintrinsic-modules-path`
"redundant". This can be avoided using the syntax
`-fintrinsic-modules-path=/path/A -fintrinsic-modules-path=/path/B`.

Author: Meinersbur

clang/include/clang/Driver/Options.td

@@ -7130,6 +7130,8 @@ def fintrinsic_modules_path : Separate<["-"], "fintrinsic-modules-path">,  Group
   HelpText<"Specify where to find the compiled intrinsic modules">,
   DocBrief<[{This option specifies the location of pre-compiled intrinsic modules,
   if they are not in the default location expected by the compiler.}]>;
+def fintrinsic_modules_path_EQ : Joined<["-"], "fintrinsic-modules-path=">,
+  Group<f_Group>, Alias<fintrinsic_modules_path>;
 
 defm backslash : OptInFC1FFlag<"backslash", "Specify that backslash in string introduces an escape character">;
 defm xor_operator : OptInFC1FFlag<"xor-operator", "Enable .XOR. as a synonym of .NEQV.">;

flang/test/Driver/intrinsic-module-path.f90

@@ -8,6 +8,7 @@
 !-----------------------------------------
 ! RUN: %flang_fc1 -fsyntax-only %s  2>&1 | FileCheck %s --allow-empty --check-prefix=WITHOUT
 ! RUN: not %flang_fc1 -fsyntax-only -fintrinsic-modules-path %S/Inputs/ %s  2>&1 | FileCheck %s --check-prefix=GIVEN
+! RUN: not %flang_fc1 -fsyntax-only -fintrinsic-modules-path=%S/Inputs/ %s  2>&1 | FileCheck %s --check-prefix=GIVEN
 
 ! WITHOUT-NOT: 'ieee_arithmetic.mod' was not found
 ! WITHOUT-NOT: 'iso_fortran_env.mod' was not found