win: Don't use rsp files when compiling gn.

Compile command lines are pretty short; even chromium doens't need rsp
files for them.

Makes the build a tiny bit faster because rsp files are written by
ninja on the critical path, and makes the build a bit easier to
work with since it's now easier to copy-paste failing compile
commands.

While here, also remove some needless braces, to make the file
more similar to linux/mac.

No intended behavior change.

Change-Id: I696b0f8d8b911e76cd5cde3c0e331375e2a766f1
Reviewed-on: https://gn-review.googlesource.com/c/gn/+/6441
Reviewed-by: Scott Graham <scottmg@chromium.org>
Commit-Queue: Nico Weber <thakis@chromium.org>

build/build_win.ninja.template

diff --git a/build/build_win.ninja.template b/build/build_win.ninja.template
index 3edfb6a..60c970f 100644
--- a/build/build_win.ninja.template
+++ b/build/build_win.ninja.template
@@ -1,25 +1,21 @@
 rule cc
-  command = ninja -t msvc -- $cc /nologo /showIncludes /FC @${out}.rsp /c ${in} /Fo${out}
-  description = CC ${out}
-  rspfile = ${out}.rsp
-  rspfile_content = ${defines} ${includes} ${cflags} ${cflags_c}
+  command = ninja -t msvc -- $cc /nologo /showIncludes /FC $defines $includes $cflags $cflags_c /c $in /Fo$out
+  description = CC $out
   deps = msvc
 
 rule cxx
-  command = ninja -t msvc -- $cxx /nologo /showIncludes /FC @${out}.rsp /c ${in} /Fo${out}
-  description = CXX ${out}
-  rspfile = ${out}.rsp
-  rspfile_content = ${defines} ${includes} ${cflags} ${cflags_cc}
+  command = ninja -t msvc -- $cxx /nologo /showIncludes /FC $defines $includes $cflags $cflags_cc /c $in /Fo$out
+  description = CXX $out
   deps = msvc
 
 rule alink_thin
-  command = ninja -t msvc -- $ar /nologo /ignore:4221 /OUT:${out} @${out}.rsp
-  description = LIB ${out}
-  rspfile = ${out}.rsp
-  rspfile_content = ${in_newline} ${libflags}
+  command = ninja -t msvc -- $ar /nologo /ignore:4221 /OUT:$out @$out.rsp
+  description = LIB $out
+  rspfile = $out.rsp
+  rspfile_content = $in_newline $libflags
 
 rule link
-  command = ninja -t msvc -- $ld /nologo /OUT:${out} /PDB:${out}.pdb @${out}.rsp
-  description = LINK ${out}
-  rspfile = ${out}.rsp
-  rspfile_content = ${in_newline} ${libs} ${solibs} ${ldflags}
+  command = ninja -t msvc -- $ld /nologo /OUT:$out /PDB:$out.pdb @$out.rsp
+  description = LINK $out
+  rspfile = $out.rsp
+  rspfile_content = $in_newline $libs $solibs $ldflags