use exec_tools instead of tools for better RBE compatibility (#4837)

diff --git a/BUILD.bazel b/BUILD.bazel
index 914619a..35dfd66 100644
--- a/BUILD.bazel
+++ b/BUILD.bazel
@@ -82,7 +82,7 @@
     outs = ["generators.inc"],
     cmd = "$(location generate_registry_tables) --xml=$(location @spirv_headers//:spirv_xml_registry) --generator-output=$(location generators.inc)",
     cmd_bat = "$(location //:generate_registry_tables) --xml=$(location @spirv_headers//:spirv_xml_registry) --generator-output=$(location generators.inc)",
-    tools = [":generate_registry_tables"],
+    exec_tools = [":generate_registry_tables"],
 )
 
 py_binary(
@@ -96,7 +96,7 @@
     outs = ["build-version.inc"],
     cmd = "SOURCE_DATE_EPOCH=0 $(location update_build_version) $(location CHANGES) $(location build-version.inc)",
     cmd_bat = "set SOURCE_DATE_EPOCH=0  && $(location //:update_build_version) $(location CHANGES) $(location build-version.inc)",
-    tools = [":update_build_version"],
+    exec_tools = [":update_build_version"],
 )
 
 # Libraries
diff --git a/build_defs.bzl b/build_defs.bzl
index ef9a829..7189137 100644
--- a/build_defs.bzl
+++ b/build_defs.bzl
@@ -76,7 +76,7 @@
             "--core-insts-output=$(location {3}) " +
             "--operand-kinds-output=$(location {4})"
         ).format(*fmtargs),
-        tools = [":generate_grammar_tables"],
+        exec_tools = [":generate_grammar_tables"],
         visibility = ["//visibility:private"],
     )
 
@@ -113,7 +113,7 @@
             "--extension-enum-output=$(location {3}) " +
             "--enum-string-mapping-output=$(location {4})"
         ).format(*fmtargs),
-        tools = [":generate_grammar_tables"],
+        exec_tools = [":generate_grammar_tables"],
         visibility = ["//visibility:private"],
     )
 
@@ -139,7 +139,7 @@
             "--extinst-opencl-grammar=$(location {0}) " +
             "--opencl-insts-output=$(location {1})"
         ).format(*fmtargs),
-        tools = [":generate_grammar_tables"],
+        exec_tools = [":generate_grammar_tables"],
         visibility = ["//visibility:private"],
     )
 
@@ -165,7 +165,7 @@
             "--extinst-glsl-grammar=$(location {0}) " +
             "--glsl-insts-output=$(location {1})"
         ).format(*fmtargs),
-        tools = [":generate_grammar_tables"],
+        exec_tools = [":generate_grammar_tables"],
         visibility = ["//visibility:private"],
     )
 
@@ -193,7 +193,7 @@
             "--vendor-insts-output=$(location {1}) " +
             "--vendor-operand-kind-prefix={2}"
         ).format(*fmtargs),
-        tools = [":generate_grammar_tables"],
+        exec_tools = [":generate_grammar_tables"],
         visibility = ["//visibility:private"],
     )
 
@@ -216,7 +216,7 @@
             "--extinst-grammar=$< " +
             "--extinst-output-path=$(location {0})"
         ).format(*fmtargs),
-        tools = [":generate_language_headers"],
+        exec_tools = [":generate_language_headers"],
         visibility = ["//visibility:private"],
     )