libc: -x some assembly files

Not sure why the +x bit was set here, but it shouldn't be.

Bug: 358360849
Test: mma
Change-Id: I02c2f8389dd2bfbc8636c675a114403c1374fc26
diff --git a/libc/arch-x86/string/sse2-stpcpy-slm.S b/libc/arch-x86/string/sse2-stpcpy-slm.S
old mode 100755
new mode 100644
diff --git a/libc/arch-x86/string/sse2-strcpy-slm.S b/libc/arch-x86/string/sse2-strcpy-slm.S
old mode 100755
new mode 100644
diff --git a/libc/arch-x86/string/sse2-strlen-slm.S b/libc/arch-x86/string/sse2-strlen-slm.S
old mode 100755
new mode 100644
diff --git a/libc/arch-x86/string/sse2-strncpy-slm.S b/libc/arch-x86/string/sse2-strncpy-slm.S
old mode 100755
new mode 100644
diff --git a/libc/arch-x86/string/sse4-memcmp-slm.S b/libc/arch-x86/string/sse4-memcmp-slm.S
old mode 100755
new mode 100644
diff --git a/libc/arch-x86/string/sse4-wmemcmp-slm.S b/libc/arch-x86/string/sse4-wmemcmp-slm.S
old mode 100755
new mode 100644