libc: simplify ssse3 detection

Since ssse3 is required as part of Android's ABI, even for 32-bit x86
(https://developer.android.com/ndk/guides/abis#sa), we can simplify
these ifuncs away.

Bug: 358360849
Test: mma
Change-Id: Ife68c7f492cc1b179aa332c12ab35b2ad6b9795a
diff --git a/libc/arch-x86/string/ssse3-strcat-atom.S b/libc/arch-x86/string/ssse3-strcat-atom.S
index 8d8e89d..b851d9e 100644
--- a/libc/arch-x86/string/ssse3-strcat-atom.S
+++ b/libc/arch-x86/string/ssse3-strcat-atom.S
@@ -87,7 +87,7 @@
 #define POP(REG)	popl REG; CFI_POP (REG)
 
 #ifndef STRCAT
-# define STRCAT	strcat_ssse3
+# define STRCAT	strcat
 #endif
 
 #define PARMS	4